DebianDebian GNU/LinuxGNU/Linux portport forfor RISCRISC-V-V 64-bits64-bits
Manuel A. Fernandez Montecelo
➢Goals of this project ➢Why a Debian Port for RISC-V? ➢What is Debian? ➢What is a Debian Port? ➢The Plan ➢History / Making Of (1st and 2nd bootstrap) ➢Current Status ➢How the RISC-V community can help ➢... and what are the benefits ➢Thanks ➢Questions / comments
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 2/46 GoalsGoals ofof thisthis projectproject
➢To have Debian ready to install & run on RISC-V based systems
➢Fully integrated with Debian infrastructure ➢Not a “one shot”, but continously updated
➢With time, to make it as well supported as “the big ones” ➢i386, x86_64 (“amd64” in Debian), arm64, ppc64el
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 3/46 WhyWhy aa DebianDebian PortPort forfor RISC-V?RISC-V? (1)(1)
➢Personal reasons: ➢Interested in both Debian and RISC-V ➢I’m already a Debian Developer ➢I like RISC-V design and goals, started following in 2014 ➢They are a good fit, philosophically and technically ➢And I would like to improve and help to grow both projects ➢I worked previously in the OpenRISC or1k port ➢... and had lots of fun!! ➢No other major GNU/Linux distributions in sight ➢(... by the time that I started, 2014~2015) ➢And ultimately, I would like to run Free Software and Debian when I get my own RISC-V based hardware
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 4/46 WhyWhy aa DebianDebian PortPort forfor RISC-V?RISC-V? (1(1 bis)bis)
➢Personal reasons: ➢Interested in both Debian and RISC-V ➢I’m already a Debian Developer ➢I like RISC-V design and goals, started following in 2014 ➢They are a good fit, philosophically and technically ➢And I would like to improve and help to grow both projects ➢I worked previously in the OpenRISC or1k port ➢... and had lots of fun!! ➢No other major GNU/Linux distributions in sight ➢(... by the time that I started, 2014~2015) ➢And ultimately, I would like to run Free Software and Debian when I get my own on the now-existing RISC-V based hardware
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 5/46 WhyWhy aa DebianDebian PortPort forfor RISC-V?RISC-V? (2)(2)
➢Technical and philosophical reasons: ➢Debian welcomes and already supports many ports ➢Including similar architectures, active now or in the recent past, some listed from “RISC-V Genealogy”: ➢MIPS (mips, mipsel) ➢Hitachi SuperH (sh4) ➢IBM PowerPC (powerpc, ppc64, ppc64el) ➢... and DEC Alpha, SPARC (32 and 64), older ARMs, PA-RISC ➢Similar or compatible goals, and methods, e.g.: ➢Aiming for openness, freedom ➢Both based, built upon same tools ➢GNU toolchain ─among others─, Linux, FOSS ecosystem ➢Striving for good technical solutions over other considerations
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 6/46 WhatWhat isis Debian?Debian? (1)(1)
➢The Project: A community of individuals
➢Mostly volunteers ➢No overall or significant control by companies
➢... who care about Free, Open-Source Software ➢Goal: to create a full, comprehensive “Operating System” ➢Large set of software packages, coherent and well integrated ➢“stable” releases every ~2 years (also used as “rolling release”) ➢Keeping “Software Freedom” as a core goal ➢Manifesto: “... developed openly in the spirit of Linux and GNU...” ➢Social Contract ➢Debian Free Software Guidelines (DSFG)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 7/46 WhatWhat isis Debian?Debian? (2)(2)
➢Mostly known as a GNU/Linux “distribution” ➢Started by Ian Murdock in 1993 ➢First “stable” release in 1996 ➢One of the major “flavours” (.deb packages) ➢More than 27k source packages in 2018 ➢Basis of many derivatives (“downstreams”) ➢Ubuntu, Raspbian, SteamOS, Knoppix, gNewSense, Linux Mint Debian Edition, Tails...
➢...which also supports other kernels ➢Currently: FreeBSD and GNU Hurd
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 8/46 WhatWhat isis aa DebianDebian Port?Port? (1)(1)
➢In short, ABI of the combination of {computer arch + OS kernel + libc} ➢Computer architecture: ➢Many, currently and over the years (details in next slides) ➢Kernel + C library: ➢Mostly Linux + GNU libc (if not mentioned explicitly) ➢But also: ➢kFreeBSD, FreeBSD kernel + GNU libc (amd64 and i386) ➢GNU Hurd + GNU libc (i386) ➢C library: ➢GNU libc in all existing ports within the Debian infrastructure ➢But some people are interested in experiments ➢e.g. Linux + musl (libc)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 9/46 WhatWhat isis aa DebianDebian Port?Port? (2)(2)
➢Three kinds of ports: ➢Outside of Debian infrastructure ➢Some derivatives are arguably an “external” port ➢e.g. Raspbian, mostly recompilation / optimisation for Raspberry Pi ➢Anybody can start one of these without official help or coordination with Debian ➢But often there’s collaboration in one way or another ➢Unofficial / unsupported ➢Not in “stable” releases, but hosted in Debian infrastructure ➢Officially supported ➢Part of the “stable” releases and fully supported ➢Ports don’t born “fully supported” ➢they work their way up to it
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 10/46 WhatWhat isis aa DebianDebian Port?Port? (3)(3)
➢Criteria for “officially suported” ports: ➢Be able to build almost all of the “source” packages ➢Have enough people responsible for it ➢addressing issues during full Stable release cycles ➢Have hardware available, redundant, well managed, etc. ➢And in return: ➢Become part of the “stable” releases and have full support for all packages (all ports) ➢For 3-5 years (“stable” release lifetime) ➢Including security support for all, not only a “core” set of packages
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 11/46 WhatWhat isis aa DebianDebian Port?Port? (4)(4)
➢“Unofficial” or “unsupported” ports: ➢When they don’t qualify as “official” for some reason ➢Hardware not available ➢Not enough people behind ➢Many packages fail to compile ➢e.g. missing Java or Haskell ecosystem (no working compiler), no GUIs, ...
➢... but are hosted in the infrastructure: ➢Can be downloaded / upgraded from *.debian.org ➢Secure, cryptographically signed ➢Get continous updates of software packages ➢When contributors upload new versions to the archive, they are compiled automatically for all ports, within minutes/hours
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 12/46 WhatWhat isis aa DebianDebian Port?Port? (5)(5)
➢Currently active: ➢ Fully supported ports, “officially suported”: ➢amd64 (x86_64), i386 (targetting i686 nowadays) ➢arm64/armel/armhf, mips/mipsel/mips64el, ppc64el, s390x ➢Not well supported: ➢Old ones with decreasing interest or available hardware: ➢alpha, ia64, hppa, m68k, powerpc/powerpcpse/ppc64, sh4, sparc64, x32 (x86_64 with ilp32)... ➢... and new ones ➢Retired: ➢Supported once, but not in the infrastructure anymore: ➢arm/armeb (old 32 bits ABIs, LE/BE), sparc (32 bits), parisc, s390 (32 bits BE)...
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 13/46 WhatWhat isis aa DebianDebian Port?Port? (6)(6)
➢What maintainers of packages see: ➢e.g. for Firefox: https://buildd.debian.org/status/package.php?p=firefox-esr
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 14/46 WhatWhat isis aa DebianDebian Port?Port? (6)(6)
➢What maintainers of packages see: ➢e.g. for Firefox: https://buildd.debian.org/status/package.php?p=firefox-esr Port/Arch Build Build machines, logs, Name Status historic, etc.
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 15/46 WhatWhat isis aa DebianDebian Port?Port? (6)(6)
➢What maintainers of packages see: ➢e.g. for Firefox: https://buildd.debian.org/status/package.php?p=firefox-esr Port/Arch Build Build machines, logs, Name Status historic, etc.
riscv64
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 16/46 TheThe PlanPlan (1)(1)
➢Broad steps: 1)Bootstrap and create viable, basic OS disk images 2)Get it to the state of “unofficial” / “unsupported”, until all criteria for “stable” are met ➢Prepare infrastructure (e.g. auto-builders), wiki, doc, etc. ➢Import bootstrapped set in the infrastructure ➢Fully rebootstrap ➢Build as many packages as possible ➢And make sure that they work ➢Keep the port running, in good state 3)In the future, when feasible, “official” ─ as well supported as main ports
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 17/46 TheThe Plan:Plan: SoftwareSoftware decisionsdecisions (2)(2)
➢Software-wise, the target is to have a port with: ➢Linux kernel ➢GNU libc ➢GCC-based toolchain ➢LLVM available (when ready), but not the main toolchain ➢Rationale: all current and well supported Debian ports target these ➢Userland is basically the same for all Debian ports ➢including those with other kernels
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 18/46 TheThe Plan:Plan: HardwareHardware decisionsdecisions (3)(3)
➢Hardware-wise, the target is 64-bit little-endian ➢Both 64-bit and LE have been the focus for general purpose computing for years ➢Debian (Linux/Unix)-capable RISC-V hardware implement this ➢Simply, it was announced (and then became true) the most popular target capable of running general purpose OS ➢Dev boards or servers that might become available in the next few years for end-users, likely 64-bit LE too ➢RV64GC ➢As it’s the “default flavour” recommended by the people most involved ➢could be reverted if needed (e.g. popular hardware without it) ➢...or have both flavours
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 19/46 TheThe Plan:Plan: NotNot ConsideredConsidered (4)(4)
➢Why not 32-bit or 128-bit variants: ➢RISC-V side: ➢Design, toolchain and simulator support have not been explored as deeply for 32-bit, support lacking in some areas ➢RV32 hardware that appeared over time not ready for general purpose OSs ➢...and 128 is simply not realistic at this time ➢But maybe in the future? :-) ➢Debian side: ➢32-bit ports already struggle to get large packages built ➢e.g. Firefox or Chromium, LibreOffice, KDE Desktop ➢This problem will only become worse with time ➢Embedded / IoT / etc. likely not interested ➢Neither Debian nor other “full”, general purpose OSs
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 20/46 TheThe Plan:Plan: WhereWhere wewe areare nownow (5)(5)
➢Steps: 1)Bootstrap and create viable, basic OS disk images ✓ 2)Get it to the state of “unofficial” / “unsupported”, until all criteria for “stable” are met ✓ ➢Prepare infrastructure (e.g. auto-builders), wiki, doc, etc. ✓ ➢Import bootstrapped set in the infrastructure ✓ ➢Fully rebootstrap ✓ ➢Build as many packages as possible ←at this point now ➢And make sure that they work ➢Keep the port running, in good state 3)In the future, when feasible, “official” ─ as well supported as main ports
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 21/46 History:History: FirstFirst BootstrapBootstrap (1)(1)
➢Started on Nov 2014 ➢Frequent pauses in 2014~2016: ➢Waiting for Specs ready ➢Waiting for Upstreaming of toolchain, Linux, etc. ➢not impossible to progress, but very inconvenient to manage with frequent changes ➢Waiting for availabity of: ➢Emulators / simulators (mainly, Qemu), matching specs ➢Toolchain implementation, matching specs ➢Different components of the toolchain to work well with each other
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 22/46 History:History: FirstFirst BootstrapBootstrap (2)(2)
➢In mid 2016, achieved a functional base Debian system ➢By the 4th Workshop at MIT, 300~400 “essential” packages built: ➢GNU coreutils, make, gawk, bash, tar, gzip, bzip2, xz-utils, flex, bison, wget, curl, less, ... ➢media codecs (png, jpeg, flac, ogg, opus, xvid, ...) ➢dpkg, apt, gnupg, openssl, nano, text-mode web browsers ➢some X-Windows packages ➢many libraries / supporting packages ➢not all of them interesting per se, but needed by others (e.g. XML libraries, ncurses) ➢Stable enough to build successfully and cleanly hundreds of packages in “native” mode (qemu-system)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 23/46 HistoryHistory:: FirstFirst BootstrapBootstrap (3)(3)
➢In late 2016 the userland ABI changed with major breakage ➢Both Debian and Fedora (which started a few months before) stopped bootstrapping ➢activity ceased to a halt ➢In April 2017, published the packages built by then ➢http://riscv.mit.edu/ ➢About 1k in total ➢They were not usable with the toolchain after the change, so only for historic interest or private tests ➢Hiatus until late 2017/early 2018 ➢Waiting for upstreaming of the support for Linux and GNU libc and final freeze of ABI
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 24/46 History:History: SecondSecond BootstrapBootstrap (1)(1)
➢Started when GNU libc was upstreamed ➢~25 Feb~5 March: Cross-build base set of packages ➢packages included in Debian only ➢not taken from github.com/riscv ➢create system to run under qemu-system ➢~5~13 March: First “native” build ➢Use cross-built system to build packages again “natively” (under qemu-system) ➢incl. running tests when available and fixing some problems early on ➢~13~23 March: Second “native” build in clean env. ➢Isolated environment similar to “production” auto-builders ➢starting from minimal chroot, installing deps as necessary, etc ➢Also, set auto-builders to use permanently for the port
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 25/46 History:History: SecondSecond BootstrapBootstrap (2)(2)
➢(cont.): ➢23~25 March: import this 2nd “decantation” into the “debian-ports” infrastructure ➢This is the seed for a basic Debian system capable to build the rest of Debian ➢Caveats: ➢Building other packages need that they support the arch if necessary, not always the case ➢There are many dependency cycles that have to be broken ➢~25 March onwards (still at it): attempt to build the whole archive ➢Add support when necessary/missing, break dep. cycles ➢Fix packages with tests failing ➢Report bugs to Debian maintainers and upstream, etc
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 26/46 CurrentCurrent statusstatus inin aa singlesingle graphgraph
➢https://buildd.debian.org/stats/graph-ports-quarter-big.png (May 1st 2018)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 27/46 StatusStatus inin detaildetail (1)(1)
➢In number of packages, ~75% there ➢More than 9k of ~13k arch-dependent packages built ➢Also available 10~15k packages which are independent of architecture ➢These are e.g. scripts, many modules from Python, Perl, definitions of documentation (e.g. Docbook), etc. ➢Some of these don’t work if they need arch-dependent packages along their long dep chains, and are unavailable ➢As time goes on, progress slows down: ➢Often bigger packages are left, take hours/days to build, have more complex dep chains to untangle... ➢The more % built, the more has to be rebuilt when new versions are uploaded by maintainers ➢e.g. several versions of GCC per week
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 28/46 StatusStatus inin detaildetail (2)(2)
➢Packages available include: ➢Most of server-side packages ➢e.g. Apache and Nginx, mail servers, VoIP, etc. ➢Complex 3D graphics games and engines ➢e.g. OpenSceneGraph ➢Media players ➢e.g. mplayer/mpv, gstreamer, VLC being built as I write ➢Desktops ➢virtually all of XFCE, LXDE/LXQt, most of GNOME and KDE ➢Complex desktop programs ➢e.g. Gimp, Inkscape, 3D design and CAD, some Office suites ➢Many Science applications and related software ➢incl. e.g. OpenMPI
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 29/46 StatusStatus inin detaildetail (3)(3)
➢Notable exceptions: ➢Complex browsers ➢ Firefox, Chromium – the latter only available in x86+arm ➢OpenJDK with Hotspot (major project) ➢only the slower Zero available ➢Other notable languages/ecosystems missing ➢Haskell ➢NodeJS ➢Golang support not very good yet ➢Toolchain ➢LLVM (support upstream too recent) ➢GDB and Valgrind (need porting upstream too) ➢ This is the “Future Work” slide :-)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 30/46 StatusStatus inin detaildetail (4)(4)
➢In general, most packages built without modif. ➢Some would need, but they already benefit from previous ports ➢patches for other arches that can be repurposed ➢changes to build systems, conditional support for some deps ➢e.g. libseccomp not available in some ports ➢For those which need modif, usually minimal ➢disable deps much higher in the stack, not yet available ➢e.g. disable Java in gettext or libdb; disable Qt GUI in cmake ➢Some need support specific to RISC-V ➢e.g. word sizes, alignment, interpreters, memory allocators...
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 31/46 StatusStatus inin detaildetail (5)(5)
➢... so they are built, but do they work? ➢Basically... YES! ➢Stable enough to build thousands of packages ➢Most of those with testsuites, passing fully or >99.5% of cases ➢Tested by using the system everyday ➢Some tested on hardware (HiFive Unleashed, thanks to SiFive!) ➢Problems found: ➢Bugs unconvered and reported in the toolchain, miscompiling ➢Qemu crashes, bugs in FP unit, and system locks ➢Problems with timeouts ➢qemu-system emulation being too slow for some tests’ defaults ➢Problems due to implementation of emulators or OS support ➢e.g. failures with network or missing features ➢... all that is expected in a new arch, some of those still happen in mature arches also
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 32/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (6)(6)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 33/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (7)(7)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 34/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (8)(8)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 35/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (9)(9)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 36/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (10)(10)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 37/46 Status:Status: PicsPics oror ItIt Didn’tDidn’t HappenHappen (11)(11)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 38/46 HowHow thethe RISC-VRISC-V communitycommunity cancan helphelp
➢“Upstream” remaining toolchain support ➢Some pieces missing, like full Linux support, GDB, Valgrind... ➢Test and report problems ➢Many packages don’t have test suites, or have subtle problems
➢See wiki page with centralised information: ➢https://wiki.debian.org/RISC-V ➢Guides for how to install a Debian system for RISC-V ➢See progress of auto-builders and packages being stuck ➢Packages with bugs, needing work, etc.
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 39/46 ...... andand whatwhat areare thethe benefitsbenefits (1)(1)
➢Just by the Debian, Fedora and other ports being started: ➢Problems in the software stack were found ➢... and hopefully are or will be fixed
➢Packages needing support or fixes upstream that we patch will benefit all RISC-V community
➢People that learn about RISC-V through non RISC-V channels can still end up contributing to RISC-V
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 40/46 ...... andand whatwhat areare thethe benefitsbenefits (2)(2)
➢Large collection of software, useful for many reasons: ➢People more likely to pay attention to the hardware ➢Large software ecosystem is key to the success of the Raspberry Pi and similar devices ➢Easy to test hardware, base ISA, new extensions ➢ARM (the company) uses Debian as testbed for changes or fixes in the architecture/ABI, prototypes of arm64_ilp32 ➢Easy to take base OS software and optimise specific packages for specific extensions (e.g. media codecs) ➢Easy to benchmark with software in common use ➢ and avoid problems of synthetic benchmarks, as “Computer Architecture: A Quantitative Approach” would have it ;-)
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 41/46 ...... andand whatwhat areare thethe benefitsbenefits (3)(3)
➢By using the Debian port directly on your RISC-V system ➢Debian is easy to install and keep up-to-date ➢At the moment not well documented/advertised, but basically: ➢Unpack .tarball in the root filesystem; or ➢Near future: debootstrap --arch=riscv64 unstable /path/chroot \ http://ftp.ports.debian.org/debian-ports/ ➢Install software, keep system up to date easily and securely ➢apt-get install awesome-package ➢apt-get upgrade ➢Easy development for the RISC-V ecosystem ➢e.g. cross-build: $ apt-get install gcc-riscv64-linux-gnu $ riscv64-linux-gnu-gcc -o test test.c
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 42/46 WhoWho
➢From the Debian side: ➢3 people invested a lot of time for months/years now, bootstrapping and building the whole archive: ➢Karsten Merker, also active in RISC-V lists ➢Aurélien Jarno, GNU libc maintainer in Debian and responsible for debian-ports infrastructure, lots of work debugging problems in the toolchain ➢Yours truly :-) ➢Many other people (long list!) got involved and offered help along the way, thanks! ➢Many Debian contributors investigate problems, apply patches proactively/quickly on a daily basis
➢Kurt Keville, from the MIT RV128 team ➢Help with infrastructure and logistics for a long time ➢lately with auto-builders ➢Website: http://rv128.mit.edu/
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 43/46 SpecialSpecial thanksthanks
➢Steven J. Wallach (Micron) ➢Sponsoring attendance to this workshop ➢Otherwise this talk might not happen!! ➢(Please, let contributors attend workshops for free! For non- professionals it’s very taxing to reserve holidays, already arrange travel, etc.) ➢SiFive, Palmer Dabbelt in particular ➢The HiFive Unleashed and other hardware ➢Bytemark (Hosting provider) ➢For sponsoring hardware (this project and Debian) ➢Christian Svensson ➢For starting the OpenRISC or1k port, being a pleasure to work with and getting me hooked!
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 44/46 AlsoAlso thanksthanks
➢Debian contributors / community ➢For creating an amazingly useful and fun project ➢Well adapted to add new ports ➢Multi-arch, cross-compilation support ➢Helmut Grohne’s rebootstrap project
➢RISC-V contributors / community ➢For the patience of the people from the community in dealing with my requests for help, comments and patches in the early times ➢For creating another amazingly useful and fun project ➢And for the courage of starting from scratch
8th RISC-V Workshop Debian GNU/Linux port for RISC-V 64-bit 45/46 QuestionsQuestions // comments?comments?
Manuel from Barcelona (Fawlty Towers) . . . . (Sorry, could not resist, Huge Fan! :-) )
Manuel in Barcelona (first time!)
Manuel A. Fernandez Montecelo
Artwork based on “Green_Debian_2” http://collab.debian.net/si0ux/gallery/green-debian-2si?view=true http://www.linuks.mine.nu/volkany/
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