Shallow Thoughts

Akkana's Musings on Open Source, Science, and Nature.

Sun, 22 Jun 2008

Custom ringtones on a Motorola phone, from Linux

I decided to stick a tentative toe into the current millennium and get myself a cellphone.

I sense your shock and amazement -- from people who know me, that I would do such a thing, and from everybody else at the concept that there's anybody in 2008 who didn't already have one.

I really don't think cellphones are evil, honest! (Except in the hands of someone driving a car -- wouldja please just put the phone down and pay attention to the friggin' road?) The truth is that I just don't much like talking on the phone, and generally manage fine with email. The land-line phone works fine for the scant time I spend on the phone, and I have to have the land line anyway (as part of the DSL package) so why pay another monthly bill for a second phone?

Prepaid plans looked like just the ticket, and that's what I got. With a cute little Motorola V195s. New toy! Rock! It can take custom MP3 ringtones and Java games ... but of course I don't want theirs, I want to make my own. So I wanted to talk to the phone from Linux.

The charger plug was a familiar shape -- looked a lot like a standard mini USB connector. Could the hardware be that easy? Sure enough, it's a standard mini USB. Kudos to Motorola for making that so easy! Now what about software?

My initial web searches led me down a false trail paved with programs like wammu and gnokii. I learned that I needed to enable ACM in my kernel (that's the modem protocol most cellphones use over USB), so as long as I was building a new kernel anyway, I grabbed the latest tarball from kernel.org (2.6.25.7). With that done, I was able to talk to the phone with gnokii, but the heavily Nokia-oriented program didn't show me much that looked useful.

Moto4lin is the answer

I set the project aside for a while. But half a week later while looking for something else, I stumbled across moto4lin, which turned out to be exactly what I needed. I had to run as root, or else when I try to connect, it prints on stderr: 

sendControl Error:[error sending control message: Operation not permitted]
) but I'm sure that can be solved somehow.

So run as root, click Connect, click File Manager if you're not already in that mode, then click Update List and it reads the files. Once they're there, you can click around in the folder list on the left looking for the audio files (on my phone, they're in a directory called audio somewhere under C, not A). Excellent!

Creating a ringtone leads to a kernel debugging digression

Okay, now I needed a ringtone. I wanted to use a bit of birdsong, so I loaded one of the tracks I use for tweet into Audacity and fiddled semi-randomly until I figured out how to cut and save a short clip. It would only save as WAV, but lame clip.wav clip.mp3 solved that just fine.

(Update: the easiest way is to select the clip you want, then do File->Export Selection...)

Except ... somewhere along the way, the clips stopped playing. I couldn't even play the original ogg track from tweet. It *looked* like it was playing ... it found the track, printed information about it, showed a running time-counter for the appropriate amount of time ... but made no sound.

It eventually turned out that the problem was that shiny new 2.6.25.7 kernel I'd downloaded. A bug introduced in 2.6.24 to the ymfpci sound card driver makes Yamaha sound cards unable to play anything with a bitrate of 44100 (which happens to be the typical CD bitrate). After a lot of debugging I eventually filed bug 10963 with a patch that reverts the old, working code from 2.6.23.17.

Ringtone success

Okay, a typical open source digression. But while I was still trying to track down the kernel bug, I meanwhile found this Razr page that tipped me off that I might need a different bitrate for ringtones anyway. So I converted it with: 

lame -b 40 mock.wav mock.mp3
(which also made it playable on the new kernel.) I also found some useful information in the lengthy Ubuntu forums discussion of moto4lin.

In the end, I was able to transfer the file easily to the motorola phone, and to use it as my nifty new ringtone. Success! Too bad nobody ever calls me and this phone is mostly for outgoing calls ...

Now to look for some fun Java apps.

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[ 19:27 Jun 22, 2008    More linux | permalink to this entry ]

Thu, 22 May 2008

Fixing scanner permissions on Hardy

Dave needed something scanned. Oh, good! The first use of a scanner under a new distro is always an interesting test. Though the last few Ubuntu releases have been so good about making scanners "just work" that I was beginning to take scanners for granted. "Sure, no problem," I told Dave, taking the sketch he gave me.

Ha! Famous last words. For Hardy, I guess the Ubuntu folks decided that users had had it too easy for a while and it was time to throw us a challenge. Under Hardy, scanning works fine as root, but normal users can't access the scanner. sane-find-scanner sees the scanner, but xsane and the xsane-gimp plug-in can't talk to it (except as root).

It turns out the code for noticing you plugged in a scanner and setting appropriate permissions (like making it group "scanner") has been removed from udev, the obvious place for it ... and moved into hal. Except, you guessed it, whatever hal is supposed to be doing isn't working, so the device's group is never set to "scanner" to make it accessible to non-root users. Lots of people are hitting this and filing bugs (search for scanner permissions), in particular bug 121082 and bug 217571.

Fortunately, the fix is quite easy if you have a copy of your old gutsy install: just copy /etc/udev/rules.d/45-libsane.rules from gutsy to the same place on hardy. (If you don't have your gutsy udev rules handy, I attached the file to the latter of the two bugs I linked above.)

Then udev will handle your scanner just like it used to, and you don't have to wait for the hal developers to figure out what's wrong with the new hal rules.

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[ 15:56 May 22, 2008    More linux | permalink to this entry ]

Fri, 16 May 2008

How to set your time zone

My laptop's clock has been drifting. I suspect the clock battery is low (not surprising on a 7-year-old machine). But after an hour of poking and prodding, I've been unable to find a way to expose the circuit board under the keyboard, either from the top (keyboard) side -- though I know how to remove individual keycaps, thanks to a reader who sent me detailed instructions a while back (thanks, Miles!) -- or the bottom. Any expert on Vaio SR laptops know how this works?

Anyway, that means I have to check and reset the time periodically. So this morning I did a time check and found it many hours off. No, wait -- actually it was pretty close; it only looked like it was way off because the system had suddenly decided it was in UTC, not PDT. But how could I change that back?

I checked /etc/timezone -- sure enough, it was set to UTC. So I changed that, copying one from a debian machine -- "US/Pacific", but that didn't do it, even after a reboot.

I spent some time reading man hwclock -- there's a lot of good reading in that manual page, about the relation between the system (kernel) clock and the hardware clock. Did you know that you're not supposed to use the date command to set the system time while the system is running? Me neither -- I do that all the time. Hmm. Anyway, interesting reading, but nothing useful about the system time zone.

It has an extensive SEE ALSO list at the end, so I explored some of those documents. /usr/share/doc/util-linux/README.Debian.hwclock is full of lots of interesting information, well worth reading, but it didn't have the answer. man tzset sounded promising, but there was no such man page (or program) on my system. Just for the heckofit, I tried typing tz[tab] to see if I had any other timezone-related programs installed ... and found tzselect. And there was the answer, added almost as an afterthought at the end of the manual page:

Note that tzselect will not actually change the timezone for you. Use 'dpkg-reconfigure tzdata' to achieve this.
Sure enough, dpkg-reconfigure tzdata let me set the time zone. And it even seems to be remembered through a reboot.

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[ 10:04 May 16, 2008    More linux | permalink to this entry ]

Fri, 02 May 2008

Two font mysteries solved

This has been a good week for fonts: two longstanding mysteries solved.

The first concerns the bitstream vera sans mono I've been using as a terminal font in apps like rxvt and xterm. I'd been specifying it in ~/.Xdefaults like this:
XTerm*font: -bitstream-bitstream vera sans mono-bold-r-normal-*-12-*-*-*-*-*-iso10646-1

The mystery is that I'd noticed that in xterm, the font looked slightly different -- slightly uglier -- than in rxvt (both apps use the same X class name of XTerm). It was hard to put my finger on what was different -- the shape of all the letters looked the same, but it just seemed a little more ragged, and a little less compact, in xterm. I figured it was just a minor difference in their drawing code, or something.

Well, I was fiddling with fonts (trying to get the new-to-me "Inconsolata" font working) and I noticed that iso10646 bit. I didn't know what 10646 was, but shouldn't it be 8859-1 or 8859-15, the codes for the Latin-1 alphabet? After finishing up my Inconsolata experiments, when I set the font back to Vera I changed the line to XTerm*font: -bitstream-bitstream vera sans mono-bold-r-normal-*-12-*-*-*-*-*-iso8859-15 and moved on to other things.

Until the next morning, when I booted up to a surprise: my main terminal window no longer fit on the screen. It seems it had reverted to the other (uglier) version of Vera Sans Mono, which is also very slightly taller, so instead of being a couple of lines shorter than the screen height, it was a couple of lines too tall to fit.

I checked .Xdefaults -- yes, it was still Vera. What was going on? I finally remembered the one thing I had changed: the language setting on the font, from 10646-1 to 8858-15. I changed it back: sure enough, now the font was pretty again and the terminal was short enough to fit.

I fired up xfontsel and did some experimenting. It turned out the difference between the two almost-identical Vera sans mono bold roman fonts is a field xfontsel calls "spc". It can be either 'c' or 'm'. The 'c' version is the pretty, compact font; the 'm' is the uglier, taller one. For some reason, specifying 10646-1 makes "spc" default to 'c', while 8859-15 makes it default to 'm'. But specifying 'c' in the font specifier gets the good version regardless of which language is specified.

So this would work: XTerm*font: -bitstream-bitstream vera sans mono-bold-r-normal-*-12-*-*-*-c-*-*-*

But then I read up on 10646-1 and it turns out to mean "the whole unicode character set". That sounds like a good idea, so I kept it in my font specifier after all: XTerm*font: -bitstream-bitstream vera sans mono-bold-r-normal-*-12-*-*-*-c-*-iso10646-1

(For the moment I still didn't know what spc, c or n meant; read on if you're curious.)

The second insight concerned a longstanding mystery of Dave's. He has been complaining for quite a while about the way Ubuntu's modern pango-based apps all refuse to see bitmapped fonts. (It bothered me too, but less so, because the terminal and editor apps I use can see X fonts.)

Dave has an Ubuntu install on one machine that he's been upgrading release after release, which does see his bitmapped fonts. But any fresh Ubuntu installation fails to see the fonts. What was the difference?

We knew about the trick of going into /etc/fonts/conf.d, removing the symbolic link 70-yes-bitmaps.conf and replacing it with a link to /etc/fonts/conf.avail/70-yes-bitmaps.conf ... But doing that doesn't actually change anything, and bitmap fonts still don't show up.

The secret turned out to be that you need to run fc-cache -fv after changing the font/conf.d links. This apparently never happens on its own -- not on a reboot, not on installing or uninstalling font packages. Somehow it had happened once on Dave's good install, and that's why it worked there but nowhere else.

I'm not sure how anyone is supposed to find out about fc-cache -- there's no man fontconfig, and the /etc/fonts/conf.avail/README offers no clue, just misleadingly says "Fontconfig scans this directory". man fc-cache mentions /usr/share/doc/fontconfig/fontconfig-user.html, which doesn't exist; it turns out on Ubuntu it's actually /usr/share/doc/fontconfig-config/fontconfig-user.html. But wait, that's just an html-ized manual page for fonts-conf, so actually you could just run man fonts-conf ... your guess is as good as mine why the fc-cache man page sends you on a hunt for html files instead.

man fonts-conf is good reading -- it even solves the mystery of that spc parameter. It stands for spacing and can be proportional, dual-width, monospace or charcell. Aha! And there's lots more useful-looking information in that manual page as well.

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[ 14:58 May 02, 2008    More linux | permalink to this entry ]

Tue, 29 Apr 2008

How often does updatedb really need to run?

Since updating to Hardy, I've been getting mail from Anacron: 
/etc/cron.weekly/slocate:
slocate: fatal error: load_file: Could not open file: /etc/updatedb.conf: No such file or directory

That's the script that updates the database for locate, Linux's fast find system. I figured I must have screwed something up when I moved that slocate cron script from cron.daily to cron.weekly (because I hate having my machine slow to a crawl as soon as I boot it in the morning, and it doesn't bother me if the database doesn't necessarily have files added in the last day or two).

But after talking to some other folks and googling for Ubuntu bugs, I discovered I wasn't the only one getting that mail, and there was already a bug covering it. Comparing my setup with another Hardy user's, I found that the file slocate was failing to find, /etc/updatedb.conf, belongs to a different package, mlocate. If mlocate is installed, then slocate's cron script works; otherwise, it doesn't. Sounds like slocate should have a dependency that pulls in mlocate, no?

But wait, what do these two packages do? Let's try a little aptitude search locate: 

p   dlocate                         - fast alternative to dpkg -L and dpkg -S   
p   kio-locate                      - kio-slave for the locate command          
i   locate                          - maintain and query an index of a directory
p   mlocate                         - quickly find files on the filesystem based
i   slocate                         - Secure replacement of findutil's locate
Okay, forget the first two, but we have locate, mlocate, and slocate. How do they relate?

Worse, if I install mlocate (so slocate will work) and then look in my cron directories, it turns out I now have, count 'em, five different cron scripts that run updatedb. They are:

In cron.daily:

locate: 72 lines! but a lot of that is comments and pruning, and a lot of fiddling to figure out what version of the kernel is running to see whether it can pass any advanced flags when it tries to renice the process. In the end it calls updatedb.findutils (note no full path, though it uses a full path when it checks for it earlier in the script).

slocate: A much simpler but unfortunately buggy 20 lines. It checks for /etc/updatedb.conf, runs it if it exists, fiddles with ionice, checks again for /etc/updatedb.conf, and based on whether it finds it, runs either /usr/bin/slocate -u or /usr/bin/slocate -u -f proc. The latter path is what was failing and sending root mail every time the script was run.

mlocate: an even slimmer 12 line script, which checks for /usr/bin/updatedb.mlocate and, if it exists, fiddles ionice then runs /usr/bin/updatedb.mlocate.

In cron.weekly:

Two virtually identical scripts called find.notslocate and find.notslocate.dpkg-new, which differ only in dpkg-new having more elaborate ionice options. They both run updatedb. And which updatedb would that be? Probably /usr/bin/updatedb, which links to /etc/alternatives/updatedb, which probably links to either updatedb.mlocate or updatedb.slocate, whichever you've installed most recently. But in either case, it's hard to see why you'd need this script running weekly if you're already running both flavors of updatedb from other scripts cron.daily. And having two copies of the script is just plain wrong (and there was already a bug filed on it). (As long as you're poking around in cron.daily and cron.weekly, check and see if you have any more of these extra dpkg-new or dpkg-old scripts -- they might be slowing down your machine for no reason.)

Further research reveals that mlocate is a new(ish) package intended to replace slocate. (There was a long discussion of that on ubuntu-devel, leading to the replacement of slocate with mlocate very late in the Hardy development cycle. There was also lots of discussion of "tracker", apparently a GUI fast find tool that can only search in the user's home directory.)

What is this mlocate? The m stands for "merge": the advantage of mlocate is that it can merge new results into its existing database instead of replacing the whole thing every time. Sounds good, right? However, the down side is that mlocate apparently can't to purge its database of old files that no longer exist, and these files will clutter up your locate results. Running locate -e will keep them from being printed -- but there seems to be no way to set this permanently, via an environment variable or .locaterc file, nor to tell updatedb.mlocate to clean up its database. So you'll need to alias locate to locate -e if you want sensible behavior. Or go back to slocate. Sigh.

Cleaning up

The important thing is to get rid of most of those spurious updatedb cron scripts. You might choose to run updatedb daily, weekly, or only when you choose to run it; but you probably don't want five different scripts running two different versions of updatedb at different times. The packages obviously aren't cleaning up after themselves, so let's do a little manual cleanup.

That find.slocate script looks suspicious. In fact, if you run dpkg -S find.notslocate, you find out that it doesn't belong to any package -- not only should the .dpkg-old version not be there, neither should the other one! So out they go.

As for slocate and mlocate, it's important to know that the two packages can coexist: installing mlocate doesn't remove slocate or vice versa. A clean Hardy install should have only mlocate; upgrades from Gutsy are more likely to have a broken slocate.

Having both packages probably isn't what you want. So pick one, and remove or disable the other. If mlocate is what you want, apt-get purge slocate and just make sure that /etc/cron.*/slocate disappears. If you decide you want slocate, it's a little trickier since the slocate package is broken; but you can fix it by creating an empty /etc/updatedb.conf so updatedb.slocate won't fail.

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[ 20:48 Apr 29, 2008    More linux/install | permalink to this entry ]

Tue, 22 Apr 2008

Autologin changes again for Hardy's upstart

Seems like each new Ubuntu release makes a few gratuitous changes to the syntax of system files. Today's change involves autologin, controlled by the "upstart" system (here's what I wrote about the previous syntax for autologin under upstart).

The /usr/bin/loginscript still hasn't changed, and this still works: 

#! /bin/sh
/bin/login -f yourusername

But the syntax has changed a little for the getty line in /etc/event.d/tty1: respawn is now on its own line (I don't know if that matters -- I still can't find any documentation on this file's syntax, though I found a new upstart page that links to some blog entries illustrating how upstart can be used to start system daemons like dbus). And the getty now needs an exec before it. Like this: 

respawn
exec /sbin/getty -n -l /usr/bin/loginscript 38400 tty1

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[ 14:27 Apr 22, 2008    More linux | permalink to this entry ]

Sun, 20 Apr 2008

Upgrading from Ubuntu Gutsy to Hardy

I finally had a moment to upgrade my desktop to Ubuntu's "Hardy Heron". I followed the same procedure as when I went from feisty to gutsy:
  1. cp -ax / /hardy
  2. cp -ax /dev/.static/dev/* /hardy/dev/
  3. Fix up files like /hardy/etc/fstab and /boot/grub/menu.lst
  4. Reboot into the newly copied gutsy
  5. do-release-upgrade -d

It took an hour or two to pull down all the files, followed by a long interval of occasionally typing Y or N, and then I was ready to start cleaning up some of the packages I'd noticed flying by that I didn't want. Oops! I couldn't remove or install anything with apt-get, because: dpkg --configure -a
But I couldn't dpkg --configure -a because several packages were broken.

The first broken package was plucker, which apparently had failed to install any files. Its postinstall script was failing because it had no files to operate on; and then I couldn't do anything further with it because apt-get wouldn't do anything until I did a dpkg --reconfigure -a

I finally got out of that by dpkg -P plucker; then after several more dpkg --reconfigure -a rounds I was eventually able to apt-get install plucker (which installed just fine the second time).

But apt still wasn't happy, because it wanted to run the trigger for initramfs-tools, which wouldn't run because it wanted kernel modules for some specific kernel version in /lib/modules. I didn't have any kernel modules because I'm not running Ubuntu's kernel (I'm stuck on 2.6.23 because bug 10118 makes all 2.6.24 variants unable to sync with USB Palm devices). But I couldn't remove initramfs-tools because udev (along with a bunch of other less important packages) depends on it. I finally found my way out of that by removing /var/lib/dpkg/triggers/initramfs-tools. I reported it as bug 220094.

Update: I forgot to mention one important thing I hit both on this machine and earlier, on the laptop: /usr/bin/play (provided by the "sox" package) no longer works because it now depends on a zillion separate libraries. apt-get install libsox-fmt-all to get all of them.

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[ 20:02 Apr 20, 2008    More linux/install | permalink to this entry ]

Thu, 10 Apr 2008

A minimal xorg.conf

Dave has been experimenting with xorg configuration lately -- trying to figure out why the latest Xorg no longer supports 1600x1200 on his monitor. (I've looked for bug reports and found gazillions of them, all blaming it on the video card but involving three different makes of video card, so color me skeptical.)

Anyway, part of this has involved taking out parts of his /etc/X11/xorg.conf file to see which parts might be causing the problem, and he's found something interesting.

What do you suppose is the minimal useful xorg.conf file? You might suppose, oh, screen and monitor sections, an input section for the keyboard and another one for a generic mouse, and that might be all you need ... right?

Okay, try it. Let's start with a really minimal file -- nothing -- and gradually add sections. To try it, make a backup of your current xorg.conf, then zero out the file: 

cd /etc/X11
mv xorg.conf xorg.conf.sav
cp /dev/null xorg.conf

Now exit X if you hadn't already, and start it up again (or let gdm do it for you). Be prepared to do repairs from the console in case X doesn't start up: e.g. sudo cp /etc/X11/xorg.conf.bak /etc/X11/xorg.conf

What happened?

In my case, on the laptop running Hardy beta, X starts right up and looks just the same as it did before.

xorg.conf -- who needs it?

A specious question, of course, which has a perfectly good answer: anyone who needs a resolution other than whatever xorg picks as the default; anyone with additional hardware, like a wacom tablet; anyone who wants customizations like XkbOptions = ctrl:nocaps. There are lots of reasons to have an xorg.conf. But it's fun to know that at least on some machines, it's possible to run without one.

Update: turns out this is part of Ubuntu's new BulletProof X feature. It doesn't work on other distros or older versions. Thanks to James D for the tip.

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[ 10:25 Apr 10, 2008    More linux | permalink to this entry ]

k3b breaks without hal

I burned a CD for the Ubuntu hardy beta alternate installer. I used k3b since that's been a good, fairly reliable burning app with a well designed UI -- I've been using it for years despite not running a KDE desktop. I selected "Burn CD Image", reduced the speed (burning apps are always wildly optimistic about speed, with the result that they create a lot of coasters) and checked the box for "verify contents after burning".

The burn went fine, and k3b ejected the CD, then sucked it back in again for the verification stage. At that point k3b started spewing lots of errors to the terminal, things like "/dev/hdd: READ 10 failed!" and "Failed to init HAL context!" repeated many times.

How annoying! k3b has added a new dependency on hal, and although it can burn a CD just fine, without hal it then forgets where the CD drive was so it can read the CD back in to verify it.

Fortunately dd /dev/cdrw | md5sum worked fine to verify that the burn was correct. I guess it's time to investigate other CD burning programs.

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[ 10:04 Apr 10, 2008    More linux | permalink to this entry ]

Mon, 07 Apr 2008

Ubuntu "Hardy Heron"

On a lunchtime bird walk on Monday I saw one blue heron and at least five green herons (very unusuual to see so many of those). Maybe that helped prepare me for installing the latest Ubuntu beta, "Hardy Heron", Monday afternoon.

I was trying the beta primarily in the hope that it would fix a serious video out regression that appeared in Gutsy (the current Ubuntu) in January. My beloved old Vaio SR17 laptop can't switch video signals on the fly like some laptops can; I've always needed to boot it with an external monitor or projector connected. But as long as it saw a monitor at boot time, it would remember that state through many suspend cycles, so I could come out of suspend, plug in to a projector and be ready to go. But beginning some time in late January, somehow Gutsy started doing something that turned off the video signal when suspending. To talk to a projector, I could reboot with the projector connected (I hate making an audience watch that! and besides, it takes away the magic). I also discovered that switching to one of the alternate consoles, then back (ctl-alt-F2 ctl-alt-F7) got a signal going out on the video port -- but I found out the hard way, in front of an audience, that it was only a 640x480 signal, not the 1024x768 signal I expected. Not pretty! I could either go back to Feisty ... or try upgrading to Hardy.

I've already written about the handy debootstrap lightweight install process I used. (I did try the official Hardy "alternate installer" disk first, but after finishing package installation it got into a spin lock trying to configure kernel modules, so I had to pull the plug and try another approach.)

This left me with a system that was very minimal indeed, so I spent the next few hours installing packages, starting with tcsh, vim (Ubuntu's minimal install has something called vim, but it's not actually vim so you tend to get lots of errors about parsing your .vimrc until you install the real vim), acpi and acpi-support (for suspending), and the window system: xorg and friends. To get xorg, I started with: 

apt-get install xserver-xorg-video-savage xbase-clients openbox xloadimage xterm

Then there was the usual exercise of aptitude search font and installing everything on that list that seemed relevant to European languages (I don't really need to scroll through dozens of Tamil, Thai, Devanagari and Bangla fonts every time I'm looking for a fancy cursive in GIMP).

But I hit a problem with that pretty early on: turns out most of the fonts I installed weren't actually showing up in xlsfonts, xfontsel, gtkfontsel, or, most important, the little xlib program I'm using for a talk I need to give in a couple weeks. I filed it as bug 212669, but kept working on it, and when a clever person on #ubuntu+1 ("redwhitewaldo") suggested I take a look at the x-ttcidfont-conf README, that gave me enough clue to get me the rest of the way. Turns out there's a Debian bug with the solution, and the workaround is easy until the Ubuntu folks pick up the update.

I hit a few other problems, like the PCMCIA/udev problem I've described elsewhere ... but mostly, my debootstrapped Hardy Heron is working quite well.

And in case you're wondering whether Hardy fixed the video signal problem, I'm happy to say it does. Video out is working just fine.

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[ 18:31 Apr 07, 2008    More linux/install | permalink to this entry ]

Sun, 06 Apr 2008

Debootstrap

Some time ago, I wished for a simple Linux "Tarball installer", something that could install a minimal install of a Linux distribution onto an existing partition or directory, skipping all the flaky and error-prone hardware-guessing that installers do.

It turns out Debian (and therefore also Ubuntu) has had this for years, and it's totally cool. It's called debootstrap.

Some folks on the #ubuntu+1 channel told me about it, and I found a nice clear howto article on how to use it for Debian. It works just the same for Ubuntu.

First, get the .deb package for the debootstrap you want to use. Here's debootstrap for Ubuntu Hardy Heron. Install it with dpkg -i. Then run it, giving it the name of the system you want to install and the directory (or mounted partition) where you want to install it. Like this: debootstrap hardy /mnt/hda3

That's all! It fetches the files it needs from the online repositories. It takes no time at all -- this really is a minimal system.

Then you need to do some fiddling to turn it into a bootable system. That includes (all paths relative to the newly installed filesystem unless otherwise stated):

Now you're read to reboot into the new system. Of course, since this is a very minimal system, you have a lot more work to do. Hardly anything is installed, and nothing has been configured for you. Some things may be challenging (for example, as I write this, X is installed but most of the fonts aren't showing up properly, which may be a bug in Hardy).

Anyway, you can get a good start by mounting your old system's root directory and copying some starter files from there, starting with these:

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[ 12:54 Apr 06, 2008    More linux/install | permalink to this entry ]

Fri, 04 Apr 2008

Handling a network card automatically: Calling ifup from udev

I'm experimenting with Ubuntu's "Hardy Heron" beta on the laptop, and one problem I've hit is that it never configures my network card properly.

The card is a cardbus 3Com card that uses the 3c59x driver. When I plug it in, or when I boot or resume after a suspend, the card ends up in a state where it shows up in ifconfig eth0, but it isn't marked UP. ifup eth0 says it's already up; ifdown eth0 complains error: SIOCDELRT: No such process but afterward, I can run ifup eth0 and this time it works. I've made an alias, net, that does sudo ifdown eth0; sudo ifup eth0. That's silly -- I wanted to fix it so it happened automatically.

Unfortunately, there's nothing written anywhere on debugging udev. I fiddled a little with udevmonitor and udevtest /class/net/eth0 and it looked like udev was in fact running the ifup rule in /etc/udev/rules.d/85-ifupdown.rules, which calls: /sbin/start-stop-daemon --start --background --pid file /var/run/network/bogus --startas /sbin/ifup -- --allow auto $env{INTERFACE} So I tried running that by hand (with $env{INTERFACE} being eth0) and, indeed, it didn't bring the interface up.

But that suggested a fix: how about adding --force to that ifup line? I don't know why the card is already in a state where ifup doesn't want to handle it, but it is, and maybe --force would fix it. Sure enough: that worked fine, and it even works when resuming after a suspend.

I filed bug 211955 including a description of the fix. Maybe there's some reason for not wanting to use --force in 85-ifupdown (why wouldn't you always want to configure a network card when it's added and is specified as auto and allow-hotplug in /etc/network/interfaces?) but if so, maybe someone will suggest a better fix.

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[ 13:41 Apr 04, 2008    More linux | permalink to this entry ]

Tue, 05 Feb 2008

Synaptics and USB mouse simultaneously

A month or so back, I spent some time fiddling with the options for the Synaptics touchpad driver. The Alps (not Synaptics) trackpad on my laptop has always worked okay with just the standard PS/2 mouse driver, but in recent kernels it's become overly sensitive to taps, registering spurious clicks when I'm in the middle of typing a word (so suddenly I'm typing in a completely different window without knowing it).

I eventually got it working. I tried various options, but here's what I settled on: 

Section "InputDevice"
        Identifier      "Trackpad"
        Driver          "synaptics"
        Option          "SHMConfig"             "true"
        Option          "SendCoreEvents"        "true"
        Option          "Device"                "/dev/psaux"
        Option          "Protocol"              "auto-dev"
        Option          "MinSpeed"              "0.5"
        Option          "MaxSpeed"              "0.75"
# AccelFactor defaults to .0015 -- synclient -l to check
        Option          "TouchpadOff"           "2"
        Option          "Emulate3Buttons"       "true"
EndSection

Section "InputDevice"
        Identifier      "Configured Mouse"
        Driver          "mouse"
        Option          "CorePointer"
        Option          "Device"                "/dev/input/mice"
        Option          "Protocol"              "ExplorerPS/2"
        Option          "ZAxisMapping"          "4 5"
        Option          "Emulate3Buttons"       "true"
EndSection

Life was groovy (I thought). Fast forward to LCA, a few days before my talk, when I decide to verify that I can run my USB mouse and the slide-advancing presentation gizmo through a hub off the single USB port. Quel surprise: the USB mouse doesn't work at all!

I didn't really need a mouse for that presentation (it was on GIMP scripting, not GIMP image editing) so I put it on the back burner, and came back to it when I got home. As I suspected, the USB mouse was working fine if I commented out the Synaptics entry from xorg.conf; it just couldn't run both at the same time.

A little googling led me to the answer, in a thread called Can't use Synaptics TouchPad and USB Mouse -- it wasn't the first google hit for synaptics "xorg.conf" usb mouse, so perhaps this entry will help its google-fu. The important part I was missing was in the "ServerLayout" section: 

        InputDevice     "Trackpad"              "AlwaysCore"
        InputDevice     "Configured Mouse"      "CorePointer"

Adding "AlwaysCore" and "CorePointer" parts was what did the trick. Thanks to "finferflu" who posted the right answer in the thread.

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[ 21:54 Feb 05, 2008    More linux | permalink to this entry ]

Sun, 23 Dec 2007

Gutsy's persistent net rules don't persist

I use wireless so seldom that it seems like each time I need it, it's a brand new adventure finding out what has changed since the last time to make it break in a new and exciting way.

This week's wi-fi adventure involved Ubuntu's current "Gutsy Gibbon" release and my prism54 wireless card. I booted the machine, switched to the right (a href="http://shallowsky.com/linux/networkSchemes.html">network scheme, inserted the card, and ... no lights. ifconfig -a showed the card on eth1 rather than eth0.

After some fiddling, I ejected the card and re-inserted it; now ifconfig -a showed it on eth2. Each time I inserted it, the number incremented by one.

Ah, that's something I remembered from Debian Etch -- a problem with the udev "persistent net rules" file in /etc/udev.

Sure enough, /etc/udev/70-persistent-net.rules had two entries for the card, one on eth1 and the other on eth2. Ejecting and re-inserting added another one for eth3. Since my network scheme is set up to apply to eth0, this obviously wouldn't work.

A comment in that file says it's generated from 75-persistent-net-generator.rules. But unfortunately, the rules uesd by that file are undocumented and opaque -- I've never been able to figure out how to make a change in its behavior. I fiddled around for a bit, then gave up and chose the brute force solution:

And that worked fine. Without 75-persistent-net-generator.rules getting in the way, the name seen in 70-persistent-net.rules works fine and I'm able to use the network.

The weird thing about this is that I've been using Gutsy with my wired network card (a 3com) for at least a month now without this problem showing up. For some reason, the persistent net generator doesn't work for the Prism54 card though it works fine for the 3com. A scan of the Ubuntu bug repository reveals lots of other people hitting similar problems on an assortment of wireless cards; bug 153727 is a fairly typical report, but the older bug 31502 (marked as fixed) points to a likely reason this is apparently so common on wireless cards -- apparently some of them report the wrong MAC address before the firmware is loaded.

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[ 18:02 Dec 23, 2007    More linux | permalink to this entry ]

Thu, 20 Dec 2007

Smart Wrapping with Greedy and Non-Greedy Regular Expressions

I had a chance to spend a day at the AGU conference last week. The American Geophysical Union is a fabulous conference -- something like 14,000 different talks over the course of the week, on anything related to earth or planetary sciences -- geology, solar system astronomy, atmospheric science, geophysics, geochemistry, you name it.

I have no idea how regular attendees manage the information overload of deciding which talks to attend. I wasn't sure how I would, either, but I started by going through the schedule for the day I'd be there, picking out a (way too long) list of potentially interesting talks, and saving them as lines in a file.

Now I had a file full of lines like: 

1020      U22A    MS 303  Terrestrial Impact Cratering: New Insights Into the Cratering Process From Geophysics and Geochemistry II
Fine, except that I couldn't print out something like that -- printers stop at 80 columns. I could pass it through a program like "fold" to wrap the long lines, but then it would be hard to scan through quickly to find the talk titles and room numbers. What I really wanted was to wrap it so that the above line turned into something like: 
1020      U22A    MS 303  Terrestrial Impact Cratering: New Insights
                          Into the Cratering Process From Geophysics
                          and Geochemistry II
But how to do that? I stared at it for a while, trying to figure out whether there was a clever vim substitute that could handle it. I asked on a couple of IRC channels, just in case there was some amazing Linux smart-wrap utility I'd never heard of. I was on the verge of concluding that the answer was no, and that I'd have to write a python script to do the wrapping I wanted, when Mikael emitted a burst of line noise:
%s/\(.\{72\}\)\(.*\)/\1^M^I^I^I\2/

Only it wasn't line noise. Seems Mikael just happened to have been reading about some of the finer points of vim regular expressions earlier that day, and he knew exactly the trick I needed -- that .\{72\}, which matches lines that are at least 72 characters long. And amazingly, that expression did something very close to what I wanted.

Or at least the first step of it. It inserts the first line break, turning my line into 

1020      U22A    MS 303  Terrestrial Impact Cratering: New Insights
                          Into the Cratering Process From Geophysics and Geochemistry II
but I still needed to wrap the second and subsequent lines.

But that was an easier problem -- just do essentially the same thing again, but limit it to only lines starting with a tab. After some tweaking, I arrived at exactly what I wanted: 

%s/^\(.\{,65\}\) \(.*\)/\1^M^I^I^I\2/

%g/^^I^I^I.\{58\}/s/^\(.\{,55\}\) \(.*\)/\1^M^I^I^I\2/
I had to run the second line two or three times to wrap the very long lines.

Devdas helpfully translated the second one into English: "You have 3 tabs, followed by 58 characters, out of which you match the first 55 and put that bit in $1, and the capture the remaining in $2, and rewrite to $1 newline tab tab tab $2."

Here's a more detailed breakdown:

Line one:
% Do this over the whole file
s/ Begin global substitute
^ Start at the beginning of the line
\( Remember the result of the next match
.\{,65\}_ Look for up to 65 characters with a space at the end
\) \( End of remembered pattern #1, skip a space, and start remembered pattern #2
.*\) Pattern #2 includes everything to the end of the line
/ End of matched pattern; begin replacement pattern
\1^M Insert saved pattern #1 (the first 65 lines ending with a space) followed by a newline
^I^I^I\2 On the second line, insert three tabs then saved pattern #2
/ End replacement pattern

Line two:
%g/ Over the whole file, only operate on lines with this pattern
^^I^I^I Lines starting with three tabs
.\{58\}/ After the tabs, only match lines that still have at least 58 characters (this guards against wrapping already wrapped lines when it's run repeatedly)
s/ Begin global substitute
^ Start at the beginning of the line
\( Remember the result of the next match
.\{,55\} Up to 55 characters
\) \( End of remembered pattern #1, skip a space, and start remembered pattern #2
.*\) Pattern #2 includes everything to the end of the line
/ End of matched pattern; begin replacement pattern
\1^M The first pattern (up to 55 chars) is one line
^I^I^I\2 Three tabs then the second pattern
/ End replacement pattern

Greedy and non-greedy brace matches

The real key is those curly-brace expressions, \{,65\} and \{58\} -- that's how you control how many characters vim will match and whether or not the match is "greedy". Here's how they work (thanks to Mikael for explaining).

The basic expression is {M,N} -- it means between M and N matches of whatever precedes it. (Vim requires that the first brace be escaped -- \{}. Escaping the second brace is optional.) So .{M,N} can match anything between M and N characters but "prefer" N, i.e. try to match as many as possible up to N. To make it "non-greedy" (match as few as possible, "preferring" M), use .{-M,N}

You can leave out M, N, or both; M defaults to 0 while N defaults to infinity. So {} is short for {0,∞} and is equivalent to *, while {-} means {-0,∞}, like a non-greedy version of *.

Given the string: one, two, three, four, five
,.\{}, matches , two, three, four,
,.\{-}, matches , two,
,.\{5,}, matches , two, three, four,
,.\{-5,}, matches , two, three,
,.\{,2}, matches nothing
,.\{,7}, matches , two,
,.\{5,7}, matches , three,

Of course, this syntax is purely for vim; regular expressions are unfortunately different in sed, perl and every other program. Here's a fun table of regexp terms in various programs.

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[ 11:44 Dec 20, 2007    More linux/editors | permalink to this entry ]

Fri, 14 Dec 2007

XFCE dukes it out with Gnome; users lose

Looking for a volume control that might me installed on mom's XFCE4-based Xubuntu desktop, I tried running xfce4-mixer.

The mixer came up fine -- but after I exited, I discovered that my xchat had gone all wonky. None of my normal key bindings worked, my cursor was blinking, and the fonts used for tabs was about half its normal size. Over in my Firefox window, key bindings were also affected.

I've seen this sort of thing happen before with Gnome apps, and had found a way to solve it using gconf-editor. That app was not installed, so I installed it and discovered that it didn't help.

I tried killing the running gconfd-2, removing .gconf/ and .gconfd/ from my home directory, then removing the four gnome directories (.gnome/, .gnome2/, .gnome2_private/, and .gnome_private/). Nothing helped xchat (though Firefox did return to normal).

After much flailing and annoying people by restarting xchat repeatedly, it turned out the problem was that xfce-mixer had started a daemon called xfce-mcs-manager, which is like gconf, only different. Like gconf, it mucks with settings of all running gtk programs without asking first. It runs simultaneously with gconf, but overrides gconf, which in turn overrides the values set in ~/.gtkrc-2.0.

Killing xfce-mcs-manager caused my running xchat to revert to its normal settings.

... Well, *almost* revert. A few key bindings didn't get reset, as I discovered when I hit a ctrl-W to erase the last word and found myself disconnected from the channel. Another xchat restart, with xfce-mcs-manager not running, fixed that.

Aside from the ever-present issue of "Where do I look when some unfriendly program decides to change the settings in running applications?" (which begs the question, "What genius thought it would be a good idea to give any random app like a volume control the power to change settings in every other gtk application currently running on the system? And do they have their medications adjusted better now?") there's another reason this is interesting.

See, if an arbitrary app like xfce-mcs-manager can send a message to xchat to change key bindings like ctrl-W ... then maybe I could write a program that could send a similar message telling xchat to cancel those compiled-in bindings like ctrl-F and ctrl-L, ones that it doesn't allow the user to change. If I could get something like that working, I could use a standard xchat -- I'd no longer need to patch the source and build my own.

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[ 20:12 Dec 14, 2007    More linux | permalink to this entry ]

Fri, 07 Dec 2007

Bug fixes? Why would we bother to ship bug fixes?

(A culture of regressions, part 2)

I've been running on Ubuntu's latest, "Gutsy gibbon", for maybe a month now. Like any release, it has its problems that I've needed to work around. Like many distros, these problems won't be fixed before the next release. But unlike other distros, it's not just lack of developer time; it turns out Ubuntu's developers point to an official policy as a reason not to fix bugs.

Take the case of the aumix bug. Aumix just plain doesn't work in gutsy. It prints, "aumix: SOUND_MIXER_READ_DEVMASK" and exits.

This turns out to be some error in the way it was compiled. If you apt-get the official ubuntu sources, build the package and install it yourself, it works fine. So somehow they got a glitch during the process of building it, and produced a bad binary.

(Minor digression -- does that make this a GPL violation? Shipping sources that don't match the distributed binary? No telling what sources were used to produce the binary in Gutsy. Not that anyone would actually want the sources for the broken aumix, of course.)

It's an easy fix, right? Just rebuild the binary from the source in the repository, and push it to the servers.

Apparently not. A few days ago, Henrik Nilsen Omma wrote in the bug:

This bug was nominated for Gutsy but does currently not qualify for a 7.10 stable release update (SRU) and the nomination is therefore declined. According the the SRU policy, the fix should already be deployed and tested in the current development version before an update to the stable releases will be considered. [ ... ] See: https://wiki.ubuntu.com/StableReleaseUpdates.

Of course, I clicked on the link to receive enlightenment. Ubuntu's Stable Release page explains

Users of the official release, in contrast, expect a high degree of stability. They use their Ubuntu system for their day-to-day work, and problems they experience with it can be extremely disruptive. Many of them are less experienced with Ubuntu and with Linux, and expect a reliable system which does not require their intervention.
by way of explaining the official Ubuntu policy on updates:
Stable release updates will, in general, only be issued in order to fix high-impact bugs. Examples of such bugs include:
  • Bugs which may, under realistic circumstances, directly cause a security vulnerability
  • Bugs which represent severe regressions from the previous release of Ubuntu
  • Bugs which may, under realistic circumstances, directly cause a loss of user data

Clearly aumix isn't a security vulnerability or a loss of user data. But I could make a good argument that a package that doesn't work ... ever ... for anyone ... constitutes a severe regression from the previous version of that package.

Ubuntu apparently thinks that users get used to packages not working, and grow to like it. I guess that if you actually fixed packages that you broke, that would be disruptive to users of the stable release.

I'm trying to picture these Ubuntu target users, who embrace regressions and get upset when something that doesn't work at all gets fixed so that it works as it did in past releases. I can't say I've ever actually met a user like that myself. But evidently the Ubuntu Updates Team knows better.

Update: I just have to pass along Dave's comment: "When an organization gets to the point where it spends more energy on institutional processes for justifying not fixing something than on just fixing it -- it's over."

Update: Carla Schroder has also written about this.

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[ 10:21 Dec 07, 2007    More linux | permalink to this entry ]

Sat, 01 Dec 2007

More Tips on International Input

With what I learned last week, I've been able to type accented characters into GTK apps such as xchat, and a few other apps such as emacs. That's nice -- but I was still having trouble reading accented characters in mutt, or writing them in vim to send through mutt (darn terminal apps).

The biggest problem was the terminal. I was using urxvt, but it turns out that urxvt won't let me type any nonascii characters. It just ignores my multi-key sequences, or prints a space instead of the character I wanted. I have no idea why, but switching to plain ol' xterm solved that problem. Of course, I had to make sure that I was using a font that supported the characters I wanted (ISO 8859-1 or 8859-15 or something similar), which leaves out my favorite terminal font (Schumacher Clean bold), but Bitstream Vera Sans Mono bold is almost as readable.

Of course, it's important to have your locale variables set appropriately. There are several locale variables:

LC_CTYPE
Which encodings to use for typing and displaying characters.
LC_MESSAGES
Which translations to use, in programs that offer them.
LC_COLLATE
How to sort alphabetically (this one also affects whether ls groups capitalized filenames first).
LC_ALL
Overrides any of the others.
LANG
The default, in case none of the other variables is set.
There are a few others which control very specific features like time, numbers, money, addresses and paper size: type locale to see all of them.

Once I switched to xterm, I was able to set either LANG or LC_CTYPE to either en_US.UTF-8 or en_US.ISO-8859-1. I set LC_COLLATE and LANG or LC_MESSAGES to C, so that I get the default (usually US) translations for programs and so that ls groups all the capitalized files first.

Along the way, I learned about yet another way to type accented characters. 

setxkbmap -model pc104 -layout us -variant intl
switches to an international layout, at which point typing certain punctuation (like ' or ~) is assumed to be a prefix key. So instead of typing [Multi] ~ n, I can just type ~ n. The catch: it makes it harder to type quotes or tildes by themselves (you have to type a space after the quote or tilde).

Even faster, the international layout also offers shortcuts to many common characters with the "AltGr" key, which I'd heard about for years but never knew how to enable. AltGr is the right alt key, and typing, say, AltGr followed by n gives an ñ. You can see a full map at Wikipedia (AltGr characters are blue, quote prefixes are red).

To get back to a US non-international layout: 

setxkbmap -model pc104 -layout us

Of course, these aren't the only keyboard layouts to choose from -- there are lots, plus you can define your own. And I was going to write a little bit about that, except it turns out they've changed it all around again since I last did that two years ago (don't you love the digital world?). So that will have to wait for another time.

But the place to start exploring is /usr/share/X11/xkb. The file symbols/us contains the definitions for those US keyboards, and I believe it's included via the files in the rules directory, probably rules/base, base.xml and base.lst. From there you're on your own. But the standard layouts probably follow the ones in the Wikipedia article on keyboard layouts

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[ 15:48 Dec 01, 2007    More linux | permalink to this entry ]

Fri, 30 Nov 2007

Backing up a file system

I upgraded my system to the latest Ubuntu, "Gutsy Gibbon", recently. Of course, it's always best to make a backup before doing a major upgrade. In this case, the goal was to back up my root partition to another partition on the same disk and get it working as a bootable Ubuntu, which I could then upgrade, saving the old partition as a working backup. I'll describe here a couple of silly snags I hit, to save you from making the same mistakes.

Linux offers lots of ways to copy filesystems. I've used tar in the past, with a command like (starting in /gutsy): tar --one-file-system -cf - / | tar xvf - > /tmp/backup.out but cp seemed like an easier way, so I want to try it.

I mounted my freshly made backup partition as /gutsy and started a cp -ax /* /gutsy (-a does the right thing for permissions, owner and group, and file type; -x tells it to stay on the original filesystem). Count to ten, then check what's getting copied. Whoops! It clearly wasn't staying on the original filesystem.

It turned out my mistake was that /*. Pretty obvious in hindsight what cp was doing: for each entry in / it did a cp -ax, staying on the filesystem for that entry, not on the filesystem for /. So /home, /boot, /proc, etc. all got copied. The solution was to remove the *: cp -ax / /gutsy.

But it wasn't quite that simple. It looked like it was working -- a long wait, then cp finished and I had what looked like a nice filesystem backup. I adjusted /gutsy/etc/fstab so that it would point to the right root, set up a grub entry, and rebooted. Disaster! The boot hung right after Attached scsi generic sg0 type 0 with no indication of what was wrong.

Rebooting into the old partition told me that what's supposed to happen next is: * Setting preliminary keymap... But the crucial error message was actually several lines earlier: Warning: unable to open an initial console. It hadn't been able to open /dev/console.

Now, in the newly copied filesystem, there was no /dev/console: in fact, /dev was empty. Nothing had been copied because /dev is a virtual file system, created by udev.

But it turns out that the boot process needs some static devices in /dev, before udev has created anything. Of course, once udev's virtual filesystem has been mounted on /dev, you can no longer read whatever was in /dev on the root partition in order to copy it somewhere else. But udev nicely gives you access to it, in /dev/.static/dev. So what I needed to do to get my new partition booting was: cp -ax /dev/.static/dev/ /gutsy/dev/ With that done, I was able to boot into my new filesystem and upgrade to Gutsy.

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[ 22:48 Nov 30, 2007    More linux | permalink to this entry ]

Thu, 22 Nov 2007

Typing accented characters (for ignorant 'murricans)

Happy Thanksgiving, everyone! Today's holiday tip involves how to type international characters.

For the online Spanish class I've been taking, so far I've been able to manage without having to type characters like ñ or á. Usually, if I need one I can find it in one of the class examples, copy it, and paste it wherever I need it. But obviously that would be tedious if I needed to type much.

I hacked up a quickie workaround: a python script that shows a set of buttons, one for each accented character I'm likely to need. Clicking a button copies that character to the clipboard, so I can now paste via mouse middleclick or ctrl-V. (I'm sure that sounds pathetic to those of you who type accented characters every day, but it's not something most US English speakers need to do. And besides, now I know how to access the X clipboard from Python-GTK -- hooray for learning new things from procrastination projects!)

Anyway, Mikael Magnusson took pity on me and explained in simple language how to use the X "Multi key" to type these characters the right way (well, a right way, anyway). Since all the online instructions I've seen have been rather complicated, here are the simple instructions for any of my fellow US monolingists who'd like to expand their horizons:

First, choose a key for the "Multi key" that you're not using for anything else. A lot of people use one of the Alt or Windows keys, but I use both of those already. What I don't use is the Menu key (that little key down by the right Ctrl key, at least on my keyboard) since not many Linux apps support it anyway.

Find the keycode for that key, by firing up xev and typing the key. For my Menu key, the keycode is 117.

Now type: 

xmodmap -e "keycode 117 = Multi_key"

Now you're ready to type a sequence like: [Menu] ~ n to type an n-tilde, [Menu] ' a for an accented a, or [menu] ? ? for the upside-down question mark, in any app that supports those characters.

Of course, you don't want to type that xmodmap command every time you log in, so to make it permanent, put this in your .Xmodmap (you're on your own for figuring out whether your X environment reads .Xmodmap automatically or whether you need to tell it to run xmodmap .Xmodmap when X starts up): 

keycode 117 = Multi_key

I have one final useful international input tidbit to offer: how to type Unicode characters by number. Hold ctrl+shift+U, then release U but keep holding the other two while you type a numeric sequence. (This may only work in gtk apps.) For instance, try this: hold down ctrl and shift, then type: u 2 6 6 c. Cool, huh? You can use the "gucharmap" program to find other neat sequences (hint: View->By Unicode Block otherwise you'll never find anything).

Now it's time to check the turkey. Have a good day, everyone!

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[ 16:03 Nov 22, 2007    More linux | permalink to this entry ]

Wed, 14 Nov 2007

Proposal: A Simpler Linux Installer

I spent a couple of fruitless hours today trying to install PCLinuxOS, a well-reviewed new Linux distro, on my Vaio. I got lots of help from the nice folks on the IRC channel, and tried lots of different approaches, but no dice -- their Live CD won't boot because it doesn't grok PCMCIA CDROM drives, and they have no other installation method besides using the live CD.

Which brings me to today's question: Why do Linux distros have installers at all?

That probably sounds like a silly question. Of course you need an installer to get the system onto your disk ... don't you?

Well, yes and no. You could make it a lot simpler than anyone currently does.

What if you distributed a Linux distro as a filesystem image? Make it tar, zip, CD iso or whatever format you like -- but provide the user with a tree of files that, when copied onto a hard drive, can boot as a running Linux.

Set up this minimal installation filesystem so that when you boot into it, you get a commandline (X hasn't been configured yet) and a set of scripts that make it easy to go the rest of the way. From your running minimal system, you can configure X, set up networking, install more programs from the distro repositories (or even from a CD image), and do all the rest of the machine-specific configuration that an installer does.

The key is that this is all happening from a running system, not from some cobbled-together installer kernel or live CD.

If you have a problem with any step, you still have a basic running system, and tools to fix the problem. You avoid the usual loop:

If your X configuration fails, try running X configuration again -- no need to do another install from the beginning. If it doesn't see your network card -- ditto. Since this debugging all happens from a normal running Linux, you can use the normal Linux tools you're used to, not some busybox-based installer.

This model would be much more hardware agnostic than current installers:

Another advantage is that it makes it very easy to make a customized version of your distro: just take the basic system image, change the part that needs changing and tar it up again.

Some distros have gone a little way with this, with an installer that gives you a starter system, then scripts to download the rest -- but I've never seen one that made the minimal system available as a filesystem image, with easy instructions on going to the next step.

What about the people who aren't already running Linux or aren't comfortable writing a filesystem image to a partition?

No problem. They get a CD image with a very simple installer -- it handles the partitioning, copies the minimal install to the partition, and updates grub. It's as prone to hardware compatibility issues as any installer (though far less so than a live CD is) but it's still better than the current model, because it won't be trying to configure hardware until the user reboots into a working minimal system.

Of course, Live CDs are still cool -- on machines where they actually work -- for showing Linux to people not ready to commit to an install. But don't tie your installer to that. Give people a simpler way to install, one that's fast and straightforward and hardware agnostic and easy to understand or customize.

The tarball installer. An idea whose time has come. Now if I could just persuade the distros to offer it.

Update: a couple of people told me about Dynebolic, a distro that apparently does just that -- you install by copying a directory on the CD onto your partition, or rsyncing from their site. Nice!

Tags:
[ 22:59 Nov 14, 2007    More linux | permalink to this entry ]

Wed, 07 Nov 2007

Tried bash, went back to tcsh

I've been a tcsh user for many years. Back in the day, there were lots of reasons for preferring csh to sh, mostly having to do with command history. Most of those reasons are long gone -- modern bash and tcsh are vastly improved from those early shells, and borrow from each other, so the differences are fairly minor.

Back in July, I solved the last blocker that had been keeping me off bash, so I put some effort into migrating all my .cshrc settings into a .bashrc so I could give bash a fair shot. It almost won; but after four months, I've switched back to tcsh, due mostly to a single niggling bash bug that I just can't seem to solve. After all these years, the crucial difference is still history. Specifically, history amnesia: bash has an annoying habit of forgetting history commands just when I most want them back.

Say I type some longish command. After it runs, I hit return a couple of times, wait a while, do a couple of other things, then decide I want to call that command back from history so I can run something similar, maybe with the filename changed or a different flag. I ctrl-P or up-arrow ... and the command isn't there!

If I type history at this point, I'll see most of my command history ... with an empty line in place of the line I was hoping to repeat. The command is gone. My only option is to remember what I typed, and type it all again.

Nobody seems to know why this happens, and it's sporadic, doesn't happen every time. Friends have been able to reproduce it, so it's not just me or my weird settings. It drives me batty. It wouldn't be so bad except it always seems to happen on the tricky commands that I really didn't want to retype.

It's too bad, because otherwise I had bash nicely whipped into shape, and it does have some advantages over tcsh. Some of the tradeoffs:

tcsh wins

Of course, you bash users, set me straight if I missed out on some bash options that would have solved some of these problems. And especially if you have a clue about the evil disappearing history commands!

bash wins

Of course, bash and tcsh aren't the only shells around. From what I hear, zsh blends the good features of bash and tcsh. One of these days I'll try it and see.

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[ 21:58 Nov 07, 2007    More linux | permalink to this entry ]

Sat, 08 Sep 2007

Custom beep sounds

It's always amazed me that Linux doesn't let you customize the system beep. You can call xset b volume pitch duration to make it beep higher or lower, or you can turn it off or switch to "visual bell"; but there's nothing like the way most other OSes let you customize it to any sound you want. (Some desktops let you customize the desktop alerts, but that doesn't do anything about the beeping you get from vim, or emacs, or bash, or a hundred other programs that run in terminals.)

Today someone pointed me toward a Gentoo wiki page that led me to Fancy Beeper Daemon. This is a small kernel module that adds a device, /dev/beep, which outputs a byte every time there's a beep. You can write a very simple daemon (several samples in Python are included with the module) which reads /dev/beep and plays the sound of your choice.

I downloaded beep-2.6.15+.tar.gz, but it needed one tweak to build it under 2.6.23-rc3: I needed to add 

#include <linux/sched.h>
among the includes at the beginning of beep.c. After that, it compiled and installed just fine. Since it's a kernel module, it works in consoles as well as under X.

/dev/beep is created with owner and group root, and readable/ writable only by owner and group, so to test it I had to chmod 666 /dev/beep to run the daemon. I fixed that by making a file in /etc/udev/rules.d called 41-beep.rules, containing: 

KERNEL=="beep", GROUP="audio"

Finally, based on the nice samples that came with the module, I wrote my own very simple Python daemon, playbeepd, that uses aplay.

Lots of fun! I don't know how much I'll use it, but it's good to have the option of custom beep sounds.

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[ 20:47 Sep 08, 2007    More linux | permalink to this entry ]

Sat, 25 Aug 2007

Widescreen Monitor, Intel Graphics on Ubuntu

On a seemingly harmless trip to Fry's, my mother got a look at the 22-inch widescreen LCD monitors and decided she had to have one. (Can't blame her ... I've been feeling the urge myself lately.)

We got the lovely new monitor home, plugged it in, configured X and discovered that the screen showed severe vertical banding. It was beautiful at low resolutions, but whenever we went to the monitor's maximum resolution of 1680x1050, the bands appeared.

After lots of testing, we tentatively pinned the problem down to the motherboard. It turns out ancient machines with 1x AGP motherboards can't drive that many pixels properly, even if the video card is up to the job. Who knew?

Off we trooped to check out new computers. We'd been hinting for quite some time that it might be about time for a new machine, and Mom was ready to take the plunge (especially if it meant not having to return that beautiful monitor).

We were hoping to find something with a relatively efficient Intel Core 2 processor and Intel integrated graphics: I've been told the Intel graphics chip works well with Linux using open source drivers. (Mom, being a person of good taste, prefers Linux, and none of us wanted to wrestle with the proprietary nvidia drivers). We found a likely machine at PC Club. They were even willing to knock $60 off the price since she didn't want Windows.

But that raised a new problem. During our fiddling with her old machine, we'd tried burning a Xubuntu CD, to see if the banding problem was due to the old XFree86 she was running. Installing it hadn't worked: her CD burner claimed it burned correctly, but the resulting CD had errors and didn't pass verification. So we needed a CD burned. We asked PC Club when buying the computer whether we might burn the ISO to CD, but apparently that counts as a "data transfer" and their minimum data transfer charge is $80. A bit much.

No problem -- a friend was coming over for dinner that night, and he was kind enough to bring his Mac laptop ... and after a half hour of fiddling, we determined that his burner didn't work either (it gave a checksum error before starting the burn). He'd never tried burning a CD on that laptop.

What about Kinko's? They have lots of data services, right? Maybe they can burn an ISO. So we stopped at Kinko's after dinner. They, of course, had never heard of an ISO image and had no idea how to burn one on their Windows box. Fearing getting a disk with a filesystem containing one file named "xubuntu-7.04-alternate-i386.iso", we asked if they had a mac, since we knew how to burn an ISO there. They did, though they said sometimes the CD burner was flaky. We decided to take the risk.

Burning an ISO on a mac isn't straightforward -- you have to do things in exactly the right order. It took some fast talking to persuade them of the steps ("No, it really won't work if you insert the blank CD first. Yes, we're quite sure") and we had to wait a long time for Kinko's antivirus software to decide that Xubuntu wasn't malware, but 45 minutes and $10 later, we had a disc.

And it worked! We first set up the machine in the living room, away from the network, so we had to kill aptitude update when the install hung installing "xubuntu-desktop" at 85% (thank goodness for alternate consoles on ctl-alt-F2) but otherwise the install went just fine. We rebooted, and Xubuntu came up ... at 1280x1024, totally wrong. Fiddling with the resolution in xorg.conf didn't help; trying to autodetect the monitor with dpkg-reconfigure xorg crashed the machine and we had to power cycle.

Back to the web ... turns out that Ubuntu "Feisty" ships with a bad Intel driver. Lots of people have hit the problem, and we found a few elaborate workarounds involving installing X drivers from various places, but nothing simple. Well, we hadn't come this far to take all the hardware back now.

First we moved the machine into the computer room, hooked up networking and reinstalled xubuntu with a full network, just in case. The resolution was still wrong. Then, with Dave in the living room calling out steps off a web page he'd found, we began the long workaround process.

"First," Dave suggested, reading, "check the version of xserver-xorg-video-intel. Let's make sure we're starting with the same version this guy is."

dpkg -l xserver-xorg-video-intel ... "Uh, it isn't installed," I reported. I tried installing it. "It wants to remove xserver-xorg-video-i810." Hmm! We decided we'd better do it, since the rest of the instructions depended on having the intel, not i810, driver.

And that was all it needed! The intel driver autodetected the monitor and worked fine at 1680x1050.

So forget the elaborate instructions for trying X drivers from various sources. The problem was that xubuntu installed the wrong driver: the i810 driver instead of the more generic intel driver. (Apparently that bug is fixed for the next Ubuntu release.)

With that fix, it was only a few more minutes before Mom was happily using her new system, widescreen monitor and all.

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[ 13:23 Aug 25, 2007    More linux | permalink to this entry ]

Sat, 18 Aug 2007

The Importance of Being ESSID (simple Linux wi-fi troubleshooting)

I'm forever having problems connecting to wireless networks, especially with my Netgear Prism 54 card. The most common failure mode: I insert the card and run /etc/init.d/networking restart (udev is supposed to handle this, but that stopped working a month or so ago). The card looks like it's connecting, ifconfig eth0 says it has the right IP address and it's marked up -- but try to connect anywhere and it says "no route to host" or "Destination host unreachable".

I've seen this both on networks which require a WEP key and those that don't, and on nets where my older Prism2/Orinoco based card will connect fine.

Apparently, the root of the problem is that the Prism54 is more sensitive than the Prism2: it can see more nearby networks. The Prism2 (with the orinoco_cs driver) only sees the strongest network, and gloms onto it. But the Prism54 chooses an access point according to arcane wisdom only known to the driver developers. So even if you're sitting right next to your access point and the next one is half a block away and almost out of range, you need to specify which one you want. How do you do that? Use the ESSID.

Every wireless network has a short identifier called the ESSID to distinguish it from other nearby networks. You can list all the access points the card sees with: 

iwlist eth0 scan
(I'll be assuming eth0 as the ethernet device throughout this article. Depending on your distro and hardware, you may need to substitute ath0 or eth1 or whatever your wireless card calls itself. Some cards don't support scanning, but details like that seem to be improving in recent kernels.)

You'll probably see a lot of ESSIDs like "linksys" or "default" or "OEM" -- the default values on typical low-cost consumer access points. Of course, you can set your own access point's ESSID to anything you want.

So what if you think your wireless card should be working, but it can't connect anywhere? Check the ESSID first. Start with iwconfig: 

iwconfig eth0
iwconfig lists the access point associated with the card right now. If it's not the one you expect, there are two ways to change that.

First, change it temporarily to make sure you're choosing the right ESSID: 

iwconfig eth0 essid MyESSID

If your accesspoint requires a key, add key nnnnnnnnnn to the end of that line. Then see if your network is working.

If that works, you can make it permanent. On Debian-derived distros, just add lines to the entry in /etc/network/interfaces: 

wireless-essid MyESSID
wireless-key nnnnnnnnnn

Some older howtos may suggest an interfaces line that looks like this:
up iwconfig eth0 essid MyESSID
Don't get sucked in. This "up" syntax used to work (along with pre-up and post-up), but although man interfaces still mentions it, it doesn't work reliably in modern releases. Use wireless-essid instead.

Of course, you can also use a gooey tool like gnome-network-manager to set the essid and key. Not being a gnome user, some time ago I hacked up the beginnings of a standalone Python GTK tool to configure networks. During this week's wi-fi fiddlings, I dug it out and blew some of the dust off: wifi-picker.

You can choose from a list of known networks (including both essid and key) set up in your own configuration file, or from a list of essids currently visible to the card, and (assuming you run it as root) it can then set the essid and key to whatever you choose. For networks I use often, I prefer to set up a long-term network scheme, but it's fun to have something I can run once to show me the visible networks then let me set essid and key.

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[ 14:44 Aug 18, 2007    More linux | permalink to this entry ]

Sun, 12 Aug 2007

Powertop BOF at Linuxworld 2007

The best thing at Linuxworld was the Powertop BOF, despite the fact that it ended up stuck in a room with no projector. The presenter, Arjan van de Ven, coped well with the setback and managed just fine.

The main goal of Powertop is to find applications that are polling or otherwise waking the CPU unnecessarily, draining power when they don't need to. Most of the BOF focused on "stupid stuff": programs that wake up too often for no reason. Some examples he gave (many of these will be fixed in upcoming versions of the software):

And that's all just the desktop stuff, without getting into other polling culprits like hal and the kernel's USB system. The kernel itself is often a significant culprit: until recently, kernels woke up once a millisecond whether they needed to or not. With the recent "tickless" option that appeared in the most recent kernel, 2.6.22, the CPU won't wake up unless it needs to.

A KDE user asked if the KDE desktop was similarly bad. The answer was yes, with a caveat: Arjan said he gave a presentation a while back to a group of KDE developers, and halfway through, one of the developers interrupted him when he pointed out a problem to say "That's not true any more -- I just checked in a fix while you were talking." It's nice to hear that at least some developers care about this stuff! Arjan said most developers responded very well to patches he'd contributed to fix the polling issues.

(Of course, those of us who use lightweight window managers like openbox or fvwm have already cut out most of these gnome and kde power-suckers. The browser issues were the only ones that applied to me, and I certainly do notice firefox' polling: when the laptop gets slow, firefox is almost always the culprit, and killing it usually brings performance back.)

As for hardware, he mentioned that some linux LCD drivers don't really dim the backlight when you reduce brightness -- they just make all the pixels darker. (I've been making a point of dimming my screen when running off batteries; time to use that Kill-A-Watt and find out if it actually matters!) Wireless cards like the ipw100 use a lot of power even when not transmitting -- sometimes even more than when they're transmitting -- so turning them off can be a big help. Using a USB mouse can cut as much as half an hour off a battery. The 2.6.23 kernel has lots of new USB power saving code, which should help. Many devices have activity every millisecond, so there's lots of room to improve.

Another issue is that even if you get rid of the 10x/sec misbehavers, some applications really do need to wake up every second or so. That's not so bad by itself, but if you have lots of daemons all waking up at different times, you end up with a CPU that never gets to sleep.

The solution is to synchronize them by rounding the wakeup times to the nearest second, so that they all wake up at about the same time, and the CPU can deal with them all then go back to sleep. But there's a trick: each machine has to round to a different value. You don't want every networking application on every machine across the internet all waking up at once -- that's a good way to flood your network servers. Arjan's phrase: "You don't want to round the entire internet" [to the same value].

The solution is a new routine in glib: timeout_add_seconds. It takes a hash of the hostname (and maybe other values) and uses that to decide where to round timeouts for the current machine. If you write programs that wake up on a regular basis, check it out. In the kernel, round_jiffies does something similar.

After all the theory, we were treated to a demo of powertop in action. Not surprisingly, it looks a bit like top. High on the screen is summary information telling you how much time your CPU is spending in the various sleep states. Getting into the deeper sleep states is generally best, but it's not quite that simple: if you're only getting there for short periods, it takes longer and uses more power to get back to a running state than it would from higher sleep states.

Below that is the list of culprits: who is waking your CPU up most often? This updates every few seconds, much like the top program. Some of it's clear (names of programs or library routines); other lines are more obscure if you're not a kernel hacker, but I'm sure they can all be tracked down.

At the bottom of the screen is a geat feature: a short hint telling you how you could eliminate the current top offender (e.g. kill the process that's polling). Not only that, but in many cases powertop will do it for you at the touch of a key. Very nice! You can try disabling things and see right away whether it helped.

Arjan stepped through killing several processes and showing the power saving benefits of each one. (I couldn't help but notice, when he was done, that the remaining top offender, right above nautilus, was gnome-power-manager. Oh, the irony!)

It's all very nifty and I'm looking forward to trying it myself. Unfortunately, I can't do that on the laptop where I really care about battery life. Powertop requires a kernel API that went in with the "tickless" option, meaning it's in 2.6.22 (and I believe it's available as a patch for 2.6.21). My laptop is stuck back on 2.6.18 because of an IRQ handling bug (bug 7264). Powertop also requires ACPI, which I have to disable because of an infinite loop in kacpid (bug 8274, Ubuntu bug 75174). It's frustrating to have great performance tools like powertop available, yet not be able to use them because of kernel regressions. But at least I can experiment with it on my desktop machine.

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[ 13:06 Aug 12, 2007    More linux | permalink to this entry ]

Sat, 11 Aug 2007

Linuxworld 2007

Last week was the annual trek to Linuxworld.

There wasn't much of interest on the exhibit floor. Lots of small companies doing virtualization or sysadmin tools. The usual assortment of publishers. A few big companies, but fewer than in past years. Not much swag. Dave commented that there was a much higher "bunny quotient" this year than last (lots of perky booth bunnies, very few knowledgeable people working the floor). The ratio of Linux to Windows in the big-company booths was much lower than last year, especially at AMD and HP, who both had far more Windows machines visible than Linux ones.

The most interesting new hardware was the Palm Foleo. It looks like a very thin 10-inch screen laptop, much like my own Vaio only much thinner and lighter, with a full QWERTY keyboard with a good feel to it. The booth staff weren't very technical, but apparently it sports a 300MHz Intel processor, built-in wi-fi and bluetooth, a resolution a hair under 1024x768 (I didn't write down the exact numbers and their literature doesn't say), a claimed battery life of 5 hours, and runs a Linux from Wind River. The booth rep I talked to said it would run regular Linux apps once they were recompiled for the processor, but he didn't seem very technical and I doubt it runs X, so I'm not sure I believe that. For a claimed price of around $400 it looks potentially quite interesting.

Their glossy handout says it has VGA out and can display PowerPoint presentations, which was interesting since the only powerpoint reader I know of on Linux is OpenOffice and I don't see that running on 300MHz (considering how slow it is on my P3 700). Apparently they're using Documents To Go from DataVis, a PalmOS app.

Aside from that there wasn't much of interest going on. They split up the "Dot Org Pavilion" this year so not all the community groups were in the same place, which was a bummer -- usually that's where all the interesting booths are (local LUGs, FSF, EFF, Debian, Ubuntu and groups like that: no Mozilla booth this time around). But this year the dotorgs were too spread out to offer a good hangout spot. It didn't look like there was much of interest at the conference either: this year they gave us Exhibit Hall pass attendees a free ticket to attend one of the paid talks, and I couldn't find one on the day we attended that looked interesting enough to bother.

However, that changed at the end of the day with the BOF sessions. The Intel Powertop BOF was an easy choice -- I've been curious about Powertop ever since it was announced, and was eager to hear more about it from one of the developers. The BOF didn't disappoint, though the room did: they didn't even provide a projector (!), so we all had to cluster around the presenter's laptop when he wanted to show something. Too bad! but it didn't keep the BOF from being full of interesting information. I'll split that off into a separate article.

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[ 11:34 Aug 11, 2007    More linux | permalink to this entry ]

Sat, 28 Jul 2007

Turn off gtk cursor blink

It's a small thing, but xchat's blinking text cursor has irritated me for a while. It's not so much the blink itself that bothers me, but that it makes the mouse pointer flicker. (I have no idea why blinking the cursor should make the X mouse pointer flicker, but it was pretty clear that they were in sync.) I've also seen fingers pointed at cursor blink as a laptop battery eater (one more reason the CPU has to wake up every second or so when it might otherwise have been idling) though I've seen no numbers on how significant that might be (probably not very, on most laptops). Anyway, there are reasons enough to look into turning off the blink.

Xchat is a gtk application, of course. There are lots and lots of pages on the web telling developers about gtk's gtk-cursor-blink property (and related properties like gtk-cursor-blink-timeout) and what they do in at a library level, so it's clearly possible. But I found nothing about where a user should set these properties to make gtk find them.

Here's the answer. Add to $HOME/.gtkrc-2.0 (or any other file loaded by $HOME/.gtkrc-2.0): 

gtk-cursor-blink = 0

I had to restart X (maybe shutting down all gtk apps would have been enough) before I saw any effect.

While I was searching, I did find a nice page on How to disable blinking cursors in lots of different apps. Its gtk section didn't seem to do anything here (maybe it only works if a gnome desktop is running), but it's a good page nontheless, full of useful advice for turning off cursor blink in other programs.

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[ 19:50 Jul 28, 2007    More linux | permalink to this entry ]

Tue, 17 Jul 2007

Adventures with bash's word erase

I've been a happy csh/tcsh user for decades. But every now and then I bow to pressure and try to join the normal bash-using Linux world.

But I always come up against one problem right away: word erase (Control-W). For those who don't use ^W, suppose I type something like: 

% ls /backups/images/trips/arizona/2007
Then I suddenly realize I want utah in 2007, not arizona. In csh, I can hit ^W twice and it erases the last two words, and I'm ready to type u<tab>. In bash, ^W erases the whole path leaving only "ls", so it's no help here. It may seem like a small thing, but I use word erase hundreds of times a day and it's hard to give it up. Google was no help, except to tell me I wasn't the only one asking.

Then the other day I was chatting about this issue with a friend who uses zsh for that reason (zsh is much more flexible at defining key bindings) and someone asked, "Is that like Meta-Delete?"

It turned out that Alt-Backspace (like many Linux applications, bash calls the Alt key "Meta", and Linux often confuses Delete and Backspace) did exactly what I wanted. Very promising!

But Alt-Backspace is not easy to type, since it's not reachable from the "home" typing position. What I needed, now that I knew bash and readline had the function, was a way to bind it to ^W.

Bash's binding syntax is documented, though the functions available don't seem to be. But bind -p | grep word gave me some useful information. It seems that \C-w was bound to "unix-word-rubout" (that was the one I didn't want) whereas "\e\C-?" was bound to "backward-kill-word". ("\e\C-?" is an obscure way of saying Meta-DEL: \e is escape, and apparently bash, like emacs, treats ESC followed by a key as the same as pressing Alt and the key simultaneously. And Control-question-mark is the Delete character in ASCII.)

So my task was to bind \C-w to backward-kill-word. It looked like this ought to work: 

bind '\C-w:backward-kill-word'

... Except it didn't. bind -p | grep w showed that C-W was still bound to "unix-word-rubout".

It turned out that it was the terminal (stty) settings causing the problem: when the terminal's werase (word erase) character is set, readline hardwires that character to do unix-word-rubout and ignores any attempts to change it.

I found the answer in a bash bug report. The stty business was introduced in readline 5.0, but due to complaints, 5.1 was slated to add a way to override the stty settings. And happily, I had 5.2! So what was this new way override method? The posting gave no hint, but eventually I found it.

Put in your .inputrc: 

set bind-tty-special-chars Off

And finally my word erase worked properly and I could use bash!

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[ 15:22 Jul 17, 2007    More linux | permalink to this entry ]

Thu, 28 Jun 2007

A Quartet of Workarounds

I upgraded my laptop's Ubuntu partition from Edgy to Feisty. Debian Etch works well, but it's just too old and I can't build software like GIMP that insists on depending on cutting-edge libraries.

But Feisty is cutting edge in other ways, so it's been a week of workarounds, in two areas: Firefox and the kernel. I'll start with Firefox.

Firefox crashes playing flash

First, the way Ubuntu's Firefox crashes when running Flash. I run flashblock, fortunately, so I've been able to browse the web just fine as long as I don't click on a flashblock button. But I like being able to view the occasional youtube video, and flash 7 has worked fine for me on every distro except Ubuntu. I first saw the problem on Edgy, and upgrading to Feisty didn't cure the problem.

But it wasn't their Firefox build; my own "kitfox" firefox build crashed as well. And it wasn't their flash installation; I've never had any luck with either their adobe flash installer nor their opensource libswfdec, so I'm running the same old flash 7 plug-in that I've used all along for other distros.

To find out what was really happening, I ran Firefox from the commandline, then went to a flash page. It turned out it was triggering an X error: 

The error was: 'BadMatch (invalid parameter attributes)'.
(Details: serial 104 error_code 8 request_code 145 minor_code 3)

That gave me something to search for. It turns out there's a longstanding Ubuntu bug, 14911 filed on this issue, with several workarounds. Setting the environment variable XLIB_SKIP_ARGB_VISUALS to 1 fixed the problem, but, reading farther in the bug, I saw that the real problem was that Ubuntu's installer had, for some strange reason, configured my X to use 16 bit color instead of 24. Apparently this is pretty common, and due to some bug involving X's and Mozilla's or Flash's handling of transparency, this causes flash to crash Mozilla.

So the solution is very simple. Edit /etc/X11/xorg.conf, look for the DefaultDepth line, and if it's 16, that's your problem. Change it to 24, restart X and see if flash works. It worked for me!

Eliminating Firefox's saved session pester dialog

While I was fiddling with Firefox, Dave started swearing. "Why does Firefox always make me go through this dialog about restoring the last session? Is there a way to turn that off?"

Sure enough, there's no exposed preference for this, so I poked around about:config, searched for browser and found browser.sessionstore.resume_from_crash. Doubleclick that line to change it to false and you'll have no more pesky dialog.

For more options related to session store, check the Mozillazine Session Restore page.

Kernel: runaway kacpid

Alas, having upgraded to Feisty expressly so that I could build cutting-edge programs like GIMP, I discovered that I couldn't build anything at all. Anything that uses heavy CPU for more than a minute or two triggers a kernel daemon, kacpid, to grab most of the CPU for itself. Being part of the kernel (even though it has a process ID), kacpi is unkillable, and prevents the machine from shutting down, so once this happens the only solution is to pull the power plug.

This has actually been a longstanding Ubuntu problem (bug 75174) but it used to be that disabling acpid would stop kacpid from running away, and with feisty, that no longer helps. The bug is also kernel.org bug 8274.

The Ubuntu bug suggested that disabling cpufreq solved it for one person. Apparently the only way to do that is to build a new kernel. There followed a long session of attempted kernel building. It was tricky because of course I couldn't build on the target machine (inability to build being the problem I was trying to solve), and even if I built on my desktop machine, a large rsync of the modules directory would trigger a runaway kacpi. In the end, building a standalone kernel with no modules was the only option.

But turning off cpufreq didn't help, nor did any of the other obvious acpi options. The only option which stops kacpid is to disable acpi altogether, and use apm. I'm sorry to lose hibernate, and temperature monitoring, but that appears to be my only option with modern kernels. Sigh.

Kernel: Hangs for 2 minutes at boot time initializing sound card

While Dave and I were madly trying to find a set of config options to build a 2.6.21 that would boot on a Vaio (he was helping out with his SR33 laptop, starting from a different set of config options) we both hit, at about the same time, an odd bug: partway through boot, the kernel would initialize the USB memory stick reader: 

sd 0:0:0:0: Attached scsi removable disk sda
sd 0:0:0:0: Attached scsi generic sg0 type 0
and then it would hang, for a long time. Two minutes, as it turned out. And the messages after that were pretty random: sometimes related to the sound card, sometimes to the network, sometimes ... GConf?! (What on earth is GConf doing in a kernel boot sequence?) We tried disabling various options to try to pin down the culprit: what was causing that two minute hang?

We eventually narrowed the blame to the sound card (which is a Yamaha, using the ymfpci driver). And that was enough information for google to find this Linux Kernel Mailing List thread. Apparently the sound maintainer decided, for some reason, to make the ymfpci driver depend on an external firmware file ... and then didn't include the firmware file, nor is it included in the alsa-firmware package he references in that message. Lovely. I'm still a little puzzled about the timeout: the post does not explain why, if a firmware file isn't found on the disk, waiting for two minutes is likely to make one magically appear.

Apparently it will be fixed in 2.6.22, which isn't much help for anyone who's trying to run a kernel on any of the 2.6.21.* series in the meantime. (Isn't it a serious enough regression to fix in 2.6.21.*?) And he didn't suggest a workaround, except that alsa-firmware package which doesn't actually contain the firmware for that card. Looks like it's left to the user to make things work.

So here's what to do: it turns out that if you take a 2.6.21 kernel, and substitute the whole sound/pci/ymfpci directory from a 2.6.20 kernel source tree, it builds and boots just fine. And I'm off and running with a standalone apm kernel with no acpi; sound works, and I can finally build GIMP again.

So it's been quite a week of workarounds. You know, I used to argue with all those annoying "Linux is not ready for the desktop" people. But sometimes I feel like Linux usability is moving in the wrong direction. I try to imagine explaining to my mac-using friends why they should have to edit /etc/X11/xorg.conf because their distro set up a configuration that makes Firefox crash, or why they need to build a new kernel because the distributed ones all crash or hang ... I love Linux and don't regret using it, but I seem to need workarounds like this more often now than I did a few years ago. Sometimes it really does seem like the open source world is moving backward, not forward.

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[ 22:24 Jun 28, 2007    More linux | permalink to this entry ]

Sun, 17 Jun 2007

Openbox 3.4

It was a bit over two years ago that I switched from icewm to fvwm as my window manager. Fvwm proved to be very fast, very configurable, and "good enough" most of the time. But lately, I've found myself irritated with it, particularly with its tendency to position windows off screen (which got a lot worse in 2.5.18). It looked like it was time to try another window manager, so when I learned that the Openbox project is headed by a fellow LinuxChixor, I had to try it.

Openbox impressed me right away. I'd tried it once before, a couple of years ago, when I found it a little inconsistent and immature. It's grown up a lot since then! It's still very fast and lightweight, but it has good focus handling, excellent window positioning, a good configuration window (obconf), and a wide variety of themes which are pretty but still don't take up too much of my limited screen space.

But more important, what it has is a very active and friendly community. I hit a couple of snags, mostly having to do with focus handling while switching desktops (the problem that drove me off icewm to fvwm), so I hopped onto the IRC channel and found myself chatting with the active developers, who told me that most of my problems had already been fixed in 3.4, and there were .deb files on the website for both of the distros I'm currently using. Indeed, that cured the problem; and when I later hit a more esoteric focus bug, the developers (particularly Dana Jansens) were all over it and fixed it that same day. Wow!

Since then I've been putting it through its paces. I have yet to see a window positioned badly in normal usage, and it handles several other problems I'd been seeing with fvwm, like focus handling when popping up dialogs (all those secondary GIMP Save-as dialogs that don't get focused when they appear). It's just as flexible as fvwm was when it comes to keyboard and mouse configuration, maybe even more so (plus it has lots of useful default bindings I might not have thought of, like mousewheel bindings to change desktops or "shade" a window).

I was going to stay out of theme configuration, because there were several pretty good installed themes already. But then in response to a half-joking question on my part of whether a particular theme came in blue, someone on the IRC channel made me a custom theme file -- and I couldn't resist tweaking it from there, and discovered that tweaking openbox themes is just as easy as fiddling with its other defaults.

I don't use transparency (I find it distracting), but my husband is addicted to transparent windows, so when I noticed on the web site that openbox handles transparency I pointed him there. (He's been using an old Afterstep, from back when it was still small and light, but it's been a constant battle getting it to build under newer gccs.) He reports that openbox handles transparency as well as afterstep did, so he's switched too.

I haven't looked at the openbox code yet, but based on how fast the developers add features and fix bugs, I bet it's clean, and I hope I can contribute at some point.

Anyway, great focus handling, great window positioning, fast, lightweight, super configurable, and best of all a friendly and helpful developer and user community. What more could you ask for in a window manager? I'm an openbox convert. Thanks, Dana, Mikachu and all the rest.

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[ 13:13 Jun 17, 2007    More linux | permali