Maximilian, along with the other members of the Debian kernel team, has the overwhelming job of maintaining the Linux kernel in Debian. It s one of the largest package and certainly one where dealing with bug reports is really difficult as most of them are hardware-specific, and thus difficult to reproduce. He s very enthusiastic and energetic, and does not fear criticizing when something doesn t please him. You ll see. My questions are in bold, the rest is by Maximilian. Who are you? My name is Maximilian Attems. I am a theoretical physicist in my last year of PhD at the Technical University of Vienna. My main research area is the early phase of a Quark-Gluon Plasma as produced in heavy ion collisions at the LHC at CERN. I am developing simulations that take weeks on the Vienna Scientific Cluster (in the TOP 500 list). The rest of the lab is much less fancy and boils down to straight intel boxes without any binary blobs or external drivers (although lately we add radeon graphics for decent free 3D). Mathematica and Maple are the rare exceptions to the many dev tools of Debian (LaTeX, editors, git, IDE s, Open MPI, ..) found at the institute, as those are unfortunately yet unmatched in Free Software for symbolic computations. The lab mostly runs a combination of Debian stable (testing starting from freeze) for desktops and oldstable/stable for servers. Debian is in use for more than 10 years. So people in the institute know some ups and downs of the project. Newcomers like my room neighbors are always surprised how functional a free Debian Desktop is. What s your biggest achievement within Debian? Building lots and lots of kernels together with an growing uptake of the officially released linux images. I joined the Debian kernel team shortly after Herbert Xu departed. I had been upstream Maintainer of the linux-2.6 janitor project for almost a year brewing hundreds of small cleanups with quilt in a tree named kjt for early linux-2.6. In Debian we had lots of fun in sorting out the troubles that the long 2.5 freeze had imposed: Meaning we were sitting on a huge diverging monolithic semi-good patchset. It was great fun to prepare 2.6.8 for Sarge with a huge team enthusiastic in shipping something real close to mainline (You have to imagine that back then you had no stable or longterm release nor any useful free tools like git. This involved passing patches around, hand editing them and seeing what the result does.) From the Sarge install reports a common pattern emerged that the current Debian early userspace was causing lots of boot failures. This motivated me to develop an alternative using the new upstream initramfs features. So I got involved in early userspace. Thanks to large and active development team initramfs-tools got a nice ecosystem. It still tries to be as generic and flexible as possible and thus gains many nice features. Also H. Peter Anvin (hpa) gave me the official co-maintenance of klibc. klibc saw uptake and good patches from Google in the last 2 years. I am proud that the early userspace is working out fairly well these days, meaning you can shuffle discs around and see your box boot. Later on we focused on 2.6.18 for Etch, which turned out to a be good release and picked up by several other distributions. Only very much later we would see such a sync again. With 2.6.26 for Lenny we got somehow unlucky as we just missed the new longterm release by one release. We also pushed for another update very late (during freeze) in the release cycle, which turned out to semi-work as too much things depend on linux-2.6. For Squeeze 2.6.32 got picked thanks to discussions at Portland Linux Plumbers and it turned out to be a good release picked up by many distributions and external patchsets. The long-term support is going very well. Greg KH is doing a great job in collecting various needed fixes for it. Somehow we had hoped that the Squeeze freeze would start sooner and that the freeze duration would be shorter, since we were ready for a release starting from the actual freeze on. The only real big bastard on the cool 2.6.32 sync is Red Hat. Red Hat Enterprise 6.0 is shipping the linux-2.6 2.6.32 in obfuscated form. They released their linux-2.6 as one big tarball clashing with the spirit of the GPL. One can only mildly guess from the changelog which patches get applied. This is in sharp contrast to any previous Red Hat release and has not yet generated the sharp and snide comments in press it deserves. Red Hat should really step back and not make such stupid management moves. Next to them even the semi-maintained Oracle Unbreakable 2.6.32 branch looks better: It is git fetchable. What are your plans and those of the kernel team for Debian Wheezy? Since 2.6.32 many of the used patches landed upstream or are on the way (speakup, Kbuild Debian specific targets, ..). The proper vfs based unionfs is something we d be looking forward. We haven t yet picked the next upstream release we will base Wheezy on, so currently we can happily jump to the most recent ones. There are plans for better interaction with Debian Installer thanks to generating our udebs properly in linux-2.6 source itself. Also we are looking forward to using git as tool of maintenance. We d hope that this will also allow for even better cross distribution collaboration. Concerning early userspace I plan to release an initramfs-tools with more generic userspace for the default case and finally also a klibc only for embedded or tuning cases. What do you like most in Debian? For one thing I do like the 2 year release cycle. It is not too long to have completely outdated software and on the other hand it gives enough time to really see huge progress from release to release. Also at my institute the software is is recent enough without too much admin overhead. For servers the three years support are a bit short, but on the manageable side. I do enjoy a lot the testing distribution. For my personal use it is very stable and thus I mainly run testing on my desktop and work boxes. (Occasionally mixing in things from sid for unbreaking transition or newer security fixes). Debian is independent and not a commercial entity. I think this is its main force and even more important these days. I enjoy using the Debian platform a lot at work thus in return this motivates me to contribute to Debian itself. I also like the fact that we strive for technical correctness. Is there some recurrent problem that hinders the progress of Debian? The New Maintainer process is a strange way to discourage people to contribute to Debian. It is particularly bureaucratic and a huge waste of time both for the applicant and his manager. It should be completely thrown overboard. One needs a more scalable approach for trust and credibility that also enhances the technical knowledge for coding and packaging of the applicant. NM is currently set in stone as any outside critics is automatically rejected. Young and energetic people are crucial for Debian and the long-term viability of the project, this is the reason why I d consider the New Maintainer process as Debian s biggest problem. Note from Rapha l Hertzog: I must say I do not share this point of view on the New Maintainer process, I have witnessed lots of improvements lately thanks to the addition of the Debian Maintainer status, and to the fact that a good history of contribution can easily subsume the annoying Tasks & Skills questionnaire. Another thing I miss is professional graphics input both for the desktop theme and the website. I know that effort has been done there lately and it is good to see movement there, but the end result is still lacking. Another trouble of Debian is its marketing capabilities. It should learn to better sell itself. It is the distribution users want to run and use not the rebranded copies of itself with lock-in sugar . Debian is about choice and it offers plenty of it: it is a great default Desktop. Linus Torvalds doesn t find Debian (and/or Ubuntu) a good platform to hack on the kernel. Do you know why and what can we do about this? The Fedora linux-2.6 receives contributions from several Red Hat employed upstream sub-Maintainers. Thus it typically carries huge patches which are not yet upstream. As a consequence eventual userland troubles get revealed quite quickly and are often seen there first. The cutting edge nature of Fedora rawhide is appealing for many developers. The usual Debian package division of library development files and the library itself is traditionally an entry barrier for dev on Debian. Debian got pretty easily usable these days, although we could and should again improve a lot more in this sector. Personally I think that Linus hasn t tried Debian for years. I have the feeling that the implication of the Debian Kernel team in LKML has been on the rise. Is that true and how do you explain this? Ben Hutchings is the Nr.1 contributor for 2.6.33. He also is top listed as author of patches on stable 2.6.32. Debian is not listed as organization as many send their linux-2.6 patches from their corporate or personal email address and thus it won t be attributed to Debian. There is currently no means to see how many patches get forwarded for the stable tree, but I certainly forwarded more then fifty patches. I was very happy when Greg KH personally thanked me in the 2.6.32.12 release. In the Squeeze kernel, the firmwares have been stripped and moved into separate packages in the non-free section. What should a user do to ensure his system keeps working? There is a debconf warning on linux-2.6 installation. It is quite clear that the free linux-2.6 can t depend on the firmware of the non-free archive (also there is no strict dependency there technically). On the terminal you d also see warnings by update-initramfs on the initramfs generation for drivers included in the initramfs. The debconf warning lists the filename(s) of the missing firmware(s). One can then apt-cache search for the firmware package name and install it via the non-free repository. The check runs against the current loaded modules. The match is not 100% accurate for special cases as the one where the device might be handled well by this driver without firmware, but is accurate enough to warrant the warning. The set of virtualization technologies that the official Debian kernel supports seems to change regularly. Which of the currently available options would you recommend to users who want to build on something that will last? KVM has been a smooth ride from day zero. It almost got included instantly upstream. The uptake it has is great as it sees both dev from Intel and AMD. Together with libvirt it s management is easy. Also the performance of virtio is very good. The linux containers are the thing we are looking forward for enhanced chroots in the Wheezy schedule. They are also manageable by libvirt. Xen being the bad outside boy has an incredible shrinking patchset, thus is fair to expect to see it for Wheezy and beyond. For many it may come a bit late, but for old hardware without relevant CPU it is there. Many tend to overstate the importance of the virtualization tech. I d be much more looking forward to the better Desktop support in newer linux-2.6. The Desktop is important for linux and something that is in heavy use. The much better graphics support of the radeon and nouveau drivers:

• For Nouveau in 32 with 33 drm we could only deliver a first taste meaning something better then rusty nv.
• For Radeon the support for Evergreen and newer is only been shaping now.

The performance optimizations thanks to dcache scalability work and the neat automatic task-grouping for the CPU scheduler are very promising features for the usability of the linux desktop. Another nice to have feature is the online defrag of ext4 and its faster mkfs. Even cooler would be better scalability in ext4 (This side seems to have seen not enough effort lately). Is there someone in Debian that you admire for their contributions? Hans Peter Anvin and Ted Tso are a huge source of deep linux-2.6 knowledge and personal wisdom. I do enjoy all sorts of interactions with them. Christoph Hellwig with Matthew Wilcox and also William Irwin for setting up the Debian kernel Team. Several Debian leaders including the previous and the current one for their engagement, which very often happens behind the scene. The Debian Gnome Team work is great, also the interactions have always been always easy and a pleasure. Martin Michlmayr and previously Thiemo Seufer do an incredible job in porting Debian on funny and interesting ARM and MIPS boxes. Debian has a lot of upcoming potential on this area. I m looking forward to other young enthusiastic people in that area. Colin Watson is bridging Debian and Ubuntu, which is an immense task. Michael Prokop bases on Debian an excellent recovery boot CD: http://www.grml.org. I d be happy if any Debian Developer would work as carefully coding and working.

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Thank you to Maximilian for the time spent answering my questions. I hope you enjoyed reading his answers as I did. Subscribe to my newsletter to get my monthly summary of the Debian/Ubuntu news and to not miss further interviews. You can also follow along on Identi.ca, Twitter and Facebook.

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In addition to the ARM platform, it is now possible to emulate a MIPS (big endian) or MIPSEL (little endian) machine running Debian under QEMU. It could be used as a cheap MIPS/MIPSEL development machine to test your packages, provided that you have a not to slow i386, AMD64 or PowerPC computer. Running on an Athlon 64 X2 3800+ the emulated system is around 10% faster than my SGI Indy R4400SC 200MHz and possibly with much more RAM (my emulated system has 512 MB of RAM). Also for the ones who know about the Indy SCSI controller, the transfer rate is around 13 MB/s on the emulated system. I have written a small howto explaining how to install Debian Etch on such an emulated MIPS or MIPSEL machine, using Debian-Installer RC1, which has just been released. Thanks to Daniel Jacobowitz who has recently improved QEMU/MIPS a lot, and to Thiemo Seufer who has started the integration of the MIPS QEMU platform in Debian-Installer and in the Debian kernel. Note 1: I have written this howto very quickly, so there are probably some mistakes. Comments are welcome.
Note 2: I have updated the ARM howto to take in account improvements from Debian-Installer RC1

2.6.18-4 was uploaded on Sunday and should be soonest available after dinstall run for most archs. The ia64 build failure is fixed in svn thanks to Thiemo Seufer (ths). alpha is waiting for an updated gcc (see patch in #397139). s390 is currently broken by vserver, patch is awaited soon. linux-latest will be updated tomorrow and expect soon a 2.6.18-5, once those issues are cleared.
linux-image-2.6.18-2- is the Debian kernel team stabilized kernel. Please install it and report eventual bugs. If you know a patch from Linus git tree that fixes your problem even better name it. Thanks for your testing!
We had been quite busy to feed stable with patches that fit the Documentation/stable_kernel_rules.txt. Goodies like Xen, drm-i965 or ahci backport are shared with Fedora Core 6 release. Beyond that for example the r8169 patch series or ccisss support for 2 TB volumes got backported. Out of reach are destabilizing patches like the new 2.6.19 ACPI patches. Further backports are planed for the SUSE reiserfs 2.6.19 patches and vorlon has a fix in the pipe for the vga console driver on alpha.

or How Mozilla Corporation is FUDing on Debian. Again. This time, Christopher Beard, Mr Mozilla Marketing is talking about Firefox in Ubuntu, that it’s great, Ubuntu is a good boy, that it cooperates with Mozilla , and that by cooperating, it can use the great Firefox name and logo. To be honest, I don’t care that Ubuntu calls Firefox Firefox instead of Iceweasel or whatever. I don’t care that Ubuntu doesn’t care about freedom as much as Debian does. I could not care less. But, indeed, I do care about (yet other) false claims about Firefox in Debian. Let’s see what Christopher has to say about it:

I understand that Ubuntu is based upon Debian. Is that the same or different than the IceWeasel browser that Debian is shipping with their latest release?
It’s different. The patches that Debian applied to the Mozilla source code (which then resulted in their IceWeasel product) are more significant in scope than those in what Ubuntu is shipping (and branding as an official Mozilla Firefox release). Firefox in Ubuntu represents a somewhat more modest set of divergences from original Mozilla source code.

Let’s check out what it is about. And as I don’t want people to doubt my words, I’ll give you, readers, the ability to check for yourself what it is all about. First, please download the latest currently available patch for Firefox 2.0 beta 2 in Debian. It has been in experimental for some weeks now. It is a bit different from the patch I described earlier, so I’ll also tell you what has been changed since this 2.0b2 patch:

• security/coreconf/rules.mk is not patched for the perl dependencies thing any more because the patch (taken from bugzilla #325148) has been applied in Firefox 2.0rc1
• The patch from bugzilla #336056 has been applied because the directory in which we would build the 2.0rc1 version contained a ~ character, which would make the build fail because of this bug.
• The patch from bugzilla #294879 has been applied for obvious reasons. It has been applied later in the Firefox 2.0 release process.

(Also note that another change has been done since then, which is actually reverting a previous patch on gfx/src/gtk/mozilla-decoder.cpp, that was adding code that became dead code when we changed the way to fix the bug.) Next, please download the official and supported Firefox diff from Ubuntu. Uncompress both these diff files, and create two directories (let’s call them ubuntudiff and debdiff) which will contain the individual patches for each file. To fill these directories, please use the following commands:

$ filterdiff --strip=1 firefox_2.0+0dfsg-0ubuntu3.diff > ubuntu.diff
$ filterdiff --strip=1 firefox_1.99+2.0b2+dfsg-1.diff > deb.diff
$ cd ubuntudiff
$ splitdiff -d -a ../ubuntu.diff
$ cd ../debdiff
$ splitdiff -d -a ../deb.diff
If you don’t have the splitdiff and filterdiff utilities, you can get them from the patchutils tools (you will also need another of these tools later). Now, let’s have fun with these split patches… Files that are only patched in Debian: (excluding any file that would be in the debian subdirectory, that contains maintainer scripts for build and installation)

$ LANG=C diff -ru debdiff/ ubuntudiff/ grep "^Only in deb" grep -v debian wc -l
6
So, that’s 6 files that Debian patches that Ubuntu doesn’t. Let’s check what they are:

$ LANG=C diff -ru debdiff/ ubuntudiff/ grep "^Only in deb" grep -v debian

(reordering result for convenience)

Only in debdiff/: browser_base_content_aboutDialog.xul

Adds rows=5 to the user agent textbox so as to display the user agent string uncut by default

Only in debdiff/: content_html_content_src_nsGenericHTMLElement.cpp
Only in debdiff/: content_html_content_src_nsHTMLInputElement.cpp
Only in debdiff/: dom_src_base_nsGlobalWindow.cpp

It’s a patch I submitted in bugzilla #343953 and that got applied in Firefox 2.0. No surprise the patch is not applied on Ubuntu.

Only in debdiff/: extensions_reporter_Makefile.in

Patch I submitted in bugzilla #354413 and that got applied in Firefox 2.0.

Only in debdiff/: security_coreconf_rules.mk

Patch from bugzilla #325148 that got applied in Firefox 2.0 (see above), and a small patch to build the NSS library with debugging symbols (put -g in CFLAGS). That leaves only 2 small patches : CFLAGS = -g added to security/coreconf/rules.mk and rows=5 to browser/base/content/aboutDialog.xul Files that are only patched in Ubuntu: (same exceptions as for Debian)

$ LANG=C diff -ru debdiff/ ubuntudiff/ grep "^Only in ubuntu" grep -v debian wc -l
45
Yes, that’s right, that’s 45 files that Ubuntu patches that Debian doesn’t. Most are windows sizes and similar things that upstream can’t get right because they are values adapted to Windows, but that also includes some changes to the code and some other things. Let’s now check differences in files that are patched in both. It’s a bit of shell black magic, but you can check by hand that it does nothing wrong :

$ LANG=C diff -ru debdiff/ ubuntudiff/ filterdiff -p1 -x configure -x debian"*" lsdiff --strip=1 while read f; do diff -u debdiff/$f ubuntudiff/ awk "! /^--- ^\+\+\+ ^ ^[-+]*\@\@/ print \"$f\"; exit "; done

That gives a list of patch files that have more differences than line numbers changes, and that do not apply to the debian directory or the configure script (which is generated from configure.in), which is what we really want to compare here. You can take this list and run interdiff between these files from the ubuntudiff and debdiff directories. I’ll explain for you what these differences are:

• Makefile.in: Ubuntu adds a line in order to install the NSS include files,
• browser_app_Makefile.in: Patch from bugzilla #314927 applied by Debian
• browser_app_profile_firefox.js: (interdiff fails because the changes apply to different versions of the file) Ubuntu changes the homepage, and sets profile.allow_automigration to false,
• config_autoconf.mk.in: Ubuntu changes includedir and idldir,
• configure.in: Ubuntu changes MOZ_APP_DISPLAYNAME, and adds some echos,
• gfx_src_gtk_nsFontMetricsXft.cpp: Ubuntu sets FC_ANY_METRICS to some patterns,
• intl_lwbrk_src_nsJISx4501LineBreaker.cpp: Patch from bugzilla #161826 applied by Debian for sparc64, which is not an architecture supported by Ubuntu,
• modules_libpref_src_init_all.js: Ubuntu changes some default fonts from serif to sans-serif, while Debian changes fonts for serif, sans-serif and monospace (setting to generic names instead of Times, Helvetica and Courier) ; I think both should be applied in Debian, actually. Ubuntu also sets dom.event.contextmenu.enabled to false,
• security_nss_lib_freebl_unix_rand.c: (interdiff fails because the changes apply to different versions of the file): both patches have the exact same effect, but are different due to changes to original file between 2.0rc1 and 2.0 final.

Overall, Ubuntu applies the same set of patches as Debian, plus some more. A somewhat more modest set of divergences, huh ?!? For what it’s worth, Ubuntu, like Debian, builds its Firefox with flat chrome and pango enabled.

What’s different in the shipping Ubuntu version of Firefox than the proposed Debian version of Firefox (that didn’t ultimately ship)?
Technically, changes include fixes to the User Agent string and the feed preview, a well as addressing issues of coherent branding. More significant than any specific difference in code, however, is Ubuntu’s commitment to work together with Mozilla and our community on releases going forward to insure product quality and integrity.
Why are you working with Ubuntu when you wouldn’t work with Debian?
We did try to work with Debian and would prefer a situation in which we work together. Ultimately, Debian took a position that was consistent with their own policies, and not compatible with some of the exceptions to Mozilla trademark policies that we offered. While we understand and respect their decision not to work with us under our branding guidelines, Mozilla believes that brands like Firefox are important for consumer protection. In any event, Ubuntu developers are working closely with Mozilla developers to insure product quality and features that are what users expect when they use Mozilla Firefox, which means that they’ll ship (and will continue to ship) a fully branded version.

Reading between the lines, that means Debian is not working with Mozilla. It’s not like we’re submitting patches. No. Never. Ever. I’m also glad to hear from Asa Dotzler, in comments to Mr Beard’s article, that this great collaboration with Ubuntu will lead to patches applied to Firefox (I guess the paid Canonical employees having more time to deal with Mozilla than the volunteer Debian maintainers may have helped, especially considering they didn’t have to do all what we already prepared). Anyways, it’s not like some of the patches we sent got applied. So, while I’m at it, here is an exhaustive list of the bugs where we took or sent the patches that are applied to Iceweasel: #51429, #161826, #252033, #258429, #273524, #287150, #289394, #294879, #307168, #307418, #314927, #319012, #322806, #323114, #325148, #326245, #330628, #331781, #331785, #331818, #333289, #333308, #343953, #345077, #345079, #345080, #345413. These don’t cover the following patches (see the rationale for these in my previous article):

• security/manager/Makefile.in, security/nss/cmd/shlibsign/Makefile: Don’t build the shlib signatures, see the rationale in my previous article,
• security/nss/cmd/shlibsign/manifest.mn: Don’t build the mangle utility,
• browser/app/Makefile.in: Force linking against libxpcom.so despite -Wl,–as-needed,
• browser/app/profile/firefox.js, gfx/src/gtk/fontEncoding.properties, modules/libpref/src/init/all.js: Preferences changes,
• browser/base/content/aboutDialog.xul: That’s one of the patches that Debian applies that Ubuntu doesn’t. See above,
• config/autoconf.mk.in: Remainings of an old patch for pangocairo, which is now useless, and setting of mozappdir,
• config/rules.mk, configure.in: Patch from Thiemo Seufer to increase stability and performance on mips, useless upstream until bugzilla #258429 is fixed, but on my to_send list,
• extensions/inspector/Makefile.in: Something that should be added to #331785, but well, it’s WONTFIX, anyway,
• layout/build/Makefile.in, layout/build/nsLayoutModule.cpp: Change to the Gecko string,
• modules/libpref/src/nsPrefService.cpp: Add a preferences directory for /etc/firefox/pref,
• widget/src/gtk2/nsWindow.cpp: Extended mouse buttons support, on my to_send list,
• configure.in, xpcom/reflect/xptcall/src/md/unix/Makefile.in: Basic patch for bugzilla #343975,
• configure.in: Check for pangoxft.

It’s so great to spend a great amount of time on a package, send patches, try to understand how things work to get patches applied, and yet, see such denial and false claims about our work. So please, Christopher, Asa, and the others, just stop talking about Debian, it will be better for everyone. PS for Rob in comments out there: No, ColorZilla won’t work on Ubuntu, because of the ABI incompatibility I explained in my previous entry, that Mozilla doesn’t seem to care much about.