Category: PlanetDebian

State of software for Suspend to RAM/Disk ?

Posted on by lucas

Dear readers,

I am the mostly happy owner of a Dell Latitude D610 (the one with the ATI video card), running Debian Etch. I installed the hibernate package to try to get Suspend to RAM and to Disk to work, and Suspend to Disk worked out of the box. But Suspend to RAM didn’t work (garbled screen at resume).

I never bothered to investigate this until today, when I discovered that acpi-support provides the same functionality, and works both for Suspend to RAM and to Disk ! I’m happier now, but I would like to understand, and the world of ACPI and Suspend to RAM/Disk is very difficult to grasp for newcomers.

What is the story behind hibernate and acpi-support ? Why was this duplication of effort needed ? Also, it seems that gnome-power-manager and kpowersave provide the same functionality. Why can’t they just call the relevant acpi-support or hibernate scripts ? How do those different implementations compare (what are their main differences ?) ? Looking at the packages content, it seems that hibernate tries to be generic, while acpi-support gave up, and handles each and every laptop model differently. Correct ? Also, hibernate seems to be handling a few things better, like getting my network interface back up after hibernation.

Finally, the last question: how do one debug Suspend issues, when it fails to work ? Is there a document somewhere explaining that ?

Working evince and poppler in Debian Etch

Posted on by lucas

Evince and poppler (the library used to render PDFs) are quite outdated in etch, and fail to display correctly a number of PDF files (including PDFs generated by latex-beamer). There’s a new poppler version (0.5.x, vs 0.4.5 in etch), but it bumps the soname, so it’s a no-go.

Since I was particularly annoyed by this (I’m an evince fan), I looked at the issue, and found that entry in poppler’s changelog for version 0.5.1:

2006-02-16  Albert Astals Cid

        * qt4/src/Makefile.am:
        * qt/Makefile.am:
        * poppler/Makefile.am:
        * glib/Makefile.am: Update soname as we are not really compatible
        anymore with previous releases that had soname 0.0.0

And I thought that maybe, the soname update was not totally justified. I modified the package in experimental (v.0.5.4) to remove the soname bump, and renamed the binary packages so it becomes a drop-in replace for the version in etch.

It works fine for me with the version of evince in etch, and seems to fix at least #369164, #409758, and #410085.

Packages are available here. Of course, this is totally unsupported, and I have not done any careful testing. But it works for me until now, and I’l update this entry if I discover some problems. Also, I don’t plan to maintain this on the long term, so beware of security bugs.

Update : This breaks tetex (see #356079). Arg. I’ll have to use the experimental version…

Running Debian on your Linksys WRT54G* … sort of

Posted on by lucas

I’m the happy owner of a Linksys WRT54GL. OpenWRT is nice, but … well. Debian is just nicer. And I couldn’t resist the idea of running Debian on this little MIPS system. Since there’s clearly not enough space available on the Linksys, I decided to install etch in a chroot, that I would mount using NFS.

Joey tried that already, the Debian wiki provides some information, but I use another technique.

First, on another system (an i386, I debootstrap’ed a mipsel etch, using --foreign. This tells debootstrap not to run the second stage:
debootstrap --arch mipsel --foreign etch /space/debian-mipsel http://ftp.fr.debian.org/debian

Then, I modified /etc/exports to allow the router to mount that chroot:
/space/debian-mipsel 192.168.1.1(rw,sync,no_root_squash)

I mounted it on the router:
ipkg install kmod-nfs
insmod sunrpc
insmod lockd
insmod nfs
mount -t nfs star:/space/debian-mipsel /debian -o nolock
mount -t proc /dev/null /debian/proc

I set up some swap space on the NFS mount (mandatory, or debootstrap’s second stage will fail):
ipkg install losetup
ipkg install kmod-loop
ipkg install swap-utils
dd if=/dev/zero of=/debian/swapfile bs=1M count=100
losetup /dev/loop/0 /debian/swapfile
mkswap /dev/loop/0
swapon /dev/loop/0

I chrooted inside /debian, and ran debootstrap’s second stage:
chroot /debian /bin/bash
debootstrap/debootstrap --second-stage

When you are done playing, you can disable the swap space and umount everything:
swapoff /dev/loop/0
losetup -d /dev/loop/0
umount /debian/proc
sleep 1 # or umount /debian will fail
umount /debian

If you want to re-mount everything, all you need to do is:
insmod sunrpc
insmod lockd
insmod nfs
mount -t nfs star:/space/debian-mipsel /debian -o nolock
mount -t proc /dev/null /debian/proc
losetup /dev/loop/0 /debian/swapfile
swapon /dev/loop/0
chroot /debian /bin/bash

That first stage/second stage split in debootstrap is really cool: it’s an easy way to run Debian anywhere, only requiring to be able to chroot at some point.

ruby & native threading

Posted on by lucas

Stefano Zacchiroli said:

To balance this, according to my first read of Ruby’s threading capability, it’s my impression that not only at most one thread can execute Ruby code at a time (limitation shared by OCaml, due to the non-distributed nature of mark and sweep garbage collectors), but also a thread blocked on a syscall will block all other threads to run.

Dumb Ruby threads (but I still hope I’m wrong …)

This is not totally true:

  • Yes, Ruby threads are user-level: you won’t get speedup from dual-cores or dual-processors system. In python, this presentation claims (slide 39) that python threads are mapped to native threads, but that a giant lock always prevents the execution of more than one thread at a time (so library writers don’t have to write thread-safe code).
  • The ruby interpreter tries very hard to map blocking syscalls to their non-blocking counterparts (for example, all I/Os are passed to a select() call). This gets really dirty when you mix I/O and other syscalls. For example, see the strace output the following Ruby code: 
    require 'thread'
th1 = Thread::new do
  pid = fork { sleep 2 }
  Process::waitpid(pid)
  puts "Finished."
end
th2 = Thread::new do
  f = STDIN.read
  puts "Finished2."
end
th1.join

    select(1, [0], [], [], {0, 349})        = 0 (Timeout)
gettimeofday({1168847486, 478832}, NULL) = 0
select(1, [0], [], [], {0, 0})          = 0 (Timeout)
waitpid(25249, 0xbf926810, WNOHANG)     = 0
select(1, [0], [], [], {0, 0})          = 0 (Timeout)
gettimeofday({1168847486, 479013}, NULL) = 0
gettimeofday({1168847486, 479053}, NULL) = 0
select(1, [0], [], [], {0, 59959})      = 0 (Timeout)
gettimeofday({1168847486, 538971}, NULL) = 0
select(1, [0], [], [], {0, 41})         = 0 (Timeout)
gettimeofday({1168847486, 543017}, NULL) = 0
select(1, [0], [], [], {0, 0})          = 0 (Timeout)
waitpid(25249, 0xbf926810, WNOHANG)     = 0
select(1, [0], [], [], {0, 0})          = 0 (Timeout)
gettimeofday({1168847486, 543200}, NULL) = 0
gettimeofday({1168847486, 543240}, NULL) = 0
select(1, [0], [], [], {0, 59959})      = 0 (Timeout)
gettimeofday({1168847486, 602842}, NULL) = 0
select(1, [0], [], [], {0, 357})        = 0 (Timeout)
gettimeofday({1168847486, 606842}, NULL) = 0
select(1, [0], [], [], {0, 0})          = 0 (Timeout)

more efficient IRCing?

Posted on by lucas

I need to reconsider my current way to do IRC.

  • My main computer is a laptop, so I can’t leave my IRC client open all the time.
  • More and more, I tend to ask stuff on IRC, then I have to leave, so I never get the chance to see the answer. Being able to stay connected all the time would be much easier.
  • I’m currently using XChat, and would like to continue using it (ie: I’d prefer to avoid going back to irssi).
  • Most of the time, I’m connected to two different networks (OFTC and Freenode).
  • I tried to set up an IRC bouncer, but I had the impression that it was complex, and not very user-friendly. (Maybe I’m wrong, or maybe I should have tried a different bouncer (which one?))
  • I’ve considered running two clients: XChat for my “main client”, and irssi just for logging everything. But that’s not really optimal.

Which solution are you using? Should I really go back to using irssi? Any good example irssi configs somewhere?

Update:

  • Comments are now open (they were closed because of a broken WP plugin)
  • I used to use screen+irssi, but then, I switched to xchat. I really like xchat, have written some custom scripts for it, and would prefer to continue to use it…
  • The possible suggestions I already got are:
    • use xchat with irssi_proxy
    • use xchat with ctrlproxy (looks very nice, but RC buggy and not in etch)
    • use xchat with shroudbnc (or psybnc, or dircproxy)

    Update 2:

    Ok, due to all the praise of the screen+irssi solution, I’ll give it another try…!

Debian Package of the Day is now alive again, and needs your help!

Posted on by lucas

For those who have missed the previous blog entries: Debian Package of the Day (aka Deb-a-day) is now alive again ! There has already been several entries (published 2 times a week, on wednesdays and sundays, until we make sure that we can sustain an higher rate):

Deb-a-day is not syndicated on Planet Debian (because of the “only personal blogs” rule), but it’s syndicated on Planet Ubuntu, and it might be syndicated on Debian Times (negociations are still ongoing :-). Don’t forget to subscribe to the feed !

We (the nice team of editors) have 2 entries ready in the queue, but that’s not enough. If you discovered an interesting package through Deb-a-day, and didn’t submit an entry yet, you should really feel guilty now ! (we are especially looking for cool graphical apps, so Deb-a-day becomes less nerdy, but apps for nerds are welcomed as well, of course.)

Of Debian Etch’s quality and release schedule

Posted on by lucas

The delay of Debian Etch caught some bad press this week. Some articles compare Debian to Ubuntu (which tries hard to have fixed-time releases), and some bloggers are amused by the fact that the next Debian release was delayed “again”. There are some important points though:

  • Etch wasn’t really scheduled to be released on Dec 4th. This target date was mainly used to determine other dates in the release process, like the freeze dates.
  • Ubuntu Dapper was delayed as well, for 6 weeks. Ubuntu Edgy wasn’t delayed, but I don’t think anybody can seriously compare Ubuntu Edgy’s quality with the upcoming Debian etch’s quality: edgy was more like a technology preview.

Now, the question is: how good is Debian Etch compared to Ubuntu Dapper ? It’s difficult to compare distributions: there aren’t a lot of good metrics for this. Of course, one could compare the number of packages that fail to build from source (it’s a good indicator of something seriously wrong in a package). But a lot of work has been done on etch about this, so it wouldn’t really be fair for Ubuntu. A good alternative is debcheck.

debcheck checks that packages can be installed (i.e that their dependancies can be satisfied). It does so by analyzing the content of the Packages files. I compared the results of debcheck on etch as of today (I re-processed it, but the same results are available from qa.d.o), and of debcheck on Dapper (not including dapper-updates – I wanted to compare quality at release date). Included sections were main for etch, and main, restricted and universe for dapper (I didn’t want to consider non-free packages, since their quality tend to be lower).

Results:

4 packages have unsatisfiable Depends on etch, on i386. 49 have unsatisfiable Recommends.

In the main section of Dapper, still on i386, only one package has a problem with its Depends (it was psycopg, because its binary package python2.3-psycopg has a dependancy on python2.3-egenix-mxdatetime). 46 packages in main had unsatisfiable Recommends. This is better than Etch, of course, but Ubuntu/main is much smaller than Debian/main.

When restricted and universe are included, the results are much worse. 80 packages have unsatisfiable Depends, and 150 packages have unsatisfiable Recommends. It is worth noting that those numbers are worse than those of Debian unstable as of today (67 packages have unsat Depends, 34 have unsat Recommends).

Conclusions (sort of):

  • Using the debcheck metric (which is actually quite important, since it translates in uninstallable packages for the users), Debian etch is already of better quality than Ubuntu Dapper when it was released (again, I haven’t checked with dapper-updates included).
  • It would be great to integrate such tests into the Ubuntu release process. Fixing bug is good, but such tools help to improve the distribution quality as a whole. I’ll try to work on this for Feisty after the Etch release.

Features vs. Freedom

Posted on by lucas

Jono Bacon wrote a long blog entry on Planet Ubuntu about his vision of freedom, and how it applies to the proprietary drivers. This is a good opportunity to write sthing I wanted to write for a long time.

Ubuntu’s bug #1 is “Microsoft has a majority market share“. Well, I think that this should be of severity minor or wishlist, not critical. A better bug #1 would be “our priority is our users” (does it ring a bell ?). I find it far more important to improve the satisfaction of people already using a Linux distribution, than to try to convince others to use it.

Most users of Windows have very good reasons for using Windows, like proprietary applications that have no equivalent in the Free Software world. I don’t think that “Linux doesn’t have a 3D desktop” is the major blocker for people not using Linux. Windows doesn’t have a 3D desktop. Many Mac OS X users don’t use the 3D features. I haven’t felt the slightest need to try a 3D desktop, and I’m using GNOME/metacity, so the jump wouldn’t so hard to make to compiz.

I’m not saying that a 3D desktop is not a good idea. Of course, it would be nice to have LiveCDs that just work and start a 3D desktop, so we could show off at conferences. But I haven’t even bothered to google for such LiveCDs.

Sometimes, proprietary drivers are more needed on Linux, for example for people who bought a Wifi card without checking first if it was supported. But I don’t think that 3D graphic drivers are that important. I still hope that Ubuntu will not ship proprietary software by default, and that Ubuntu will try to help the free drivers instead.

Update: I forgot to close the comments when publishing this entry. They are closed now, but trackbacks are open if you want to write your own blog about this (I don’t think it’s necessary, all arguments have been reharsed many times already. Ah, and for the records, the free ati driver works perfectly fine and fast (using MergedFB) in my dual-screen setup (2560*1024), with xv on both monitors.

Back from the Debian QA meeting in Extremadura

Posted on by lucas

I’ve spent the last few days in Badajoz for the Debian QA meeting in Extremadura. It was my first Debian event, and it was really nice to finally meet all those developers I only knew over the Internet until then. The organisation was very good in general, and César Gómez really deserves kudos and some rest now :-)

In addition to the usual mail processing, I worked on a few things:

  • I processed some logs from a rebuilt of all packages in etch and filed about 20 RC bugs about FTBFS. I also did several libpng-related rebuilds, checking that etch packages that b-dep on it still build with the proposed new version. And I investigated a few bugs.
  • I also worked on a dirty script to generate the List of packages with problems wrt release (packages in etch with RC bugs, or packages in unstable but not in testing). See the list sorted by maintainer, and the list sorted by popcon score. Despite the unavoidable high number of false positives, I think that some maintainers were actually unaware of the status of their packages, so the list was probably useful.
  • I gave a talk about Collaborative QA. The idea is try to move from the current non-organisation (QA one by a bored developer, on his own, because the release is approaching) to a more organized structure (team ?), allowing to share the load and share information (blacklists, false positives lists, processes, etc). I’m not sure yet if this will work, because many people consider that the current way of working on QA is OK, but I’ve created the collab-qa alioth project, and will try to use it to store information about my archive rebuilds. More to come about this later.

In general, I was pleasantly surprised by the fact that all DDs there were very friendly, welcoming, etc. Quite different from the picture of the Debian project one can easily get by looking at the mailing list. It was really nice to have so many interesting discussions with interesting people.

Resurrecting “Debian package a day”, part two.

Posted on by lucas

After this blog entry, I thought for a while, and decided to take over Debian package a day. I’m well aware that it needs a lot of time, so I’ll try to make this a collaborative work:

  • It should be as easy as possible for readers to submit entries
  • There will be a team of editors, willing to dedicate some time to this on a regular basis, who will receive new entries from users, improve them and publish them.

The publishing rate should depend on the number of ready-to-go entries in the queue. Starting with publishing twice a week should be okay.

I have already started to set up a wordpress blog (using drafts to prepare entries + mails to coordinate should be enough for now ; we can always switch to something more complex later).

TODO List :

  1. Get control over the debaday.debian.net domain. I couldn’t do it directly since DAMs seem to want to wait until Christmas to deliver my Debian account, so buxy did it for me. Should resolve soon.
  2. Get added to Planet Debian and Planet Ubuntu. If the posting rate stays low, it shouldn’t be a problem, and we can always change this later.
  3. Write the initial pages explaining how to contribute, etc.
  4. Get the first entry online.
  5. Recruit editors to share the load.
  6. Wait for you to submit entries :-)

Update (08/12/06) : Debian Package of the Day won’t be added on Planet Debian: a recent discussion concluded that non-personal blogs should not be on Planet Debian. So you have to subscribe directly to its feed (if you read Planet Ubuntu, you probably don’t need to, since it was added there).