Let the JDK Hacking Begin...

OpenJDK, the open-source JDK 7 release (and no, I don't know if there's any practical difference between the two) has officially opened for business with the promotion of the "real, live" Mercurial repositories. These are the real deal, the same repositories that Sun employees will be working on as they modify the code... which means, in all reality, that there is a very tiny window of opportunity for you to check out code between changesets that are dependent on one another due to the way they've got the forest set up--if you get weird build errors, try re-fetching... but more on that later.

Think about it for a second--now, thanks to the way Mercurial handles source (a distributed source code system is different from a centralized client/server one like SVN or CVS), you can hack away on your own private build of the JDK, and still keep up to date with what Sun's doing. And, if Sun likes what you're doing, you could end up contributing back to the JDK as a whole.

You could make changes to the langtools bundle to start adding new features you think should be in Java.

You could make changes to the hotspot bundle to start exploring ways to optimize GC better.

You could fix bugs you find in the various Java libraries.

You could even add new features to the core classes that you've been saying needed to be there since Day 1.

You can start exploring the new Modules system (JSR-277) strawman implementation.

Then, you can post your diffs, or just tell people where your changesets are, and others can play with them.


Getting Started

Meanwhile, for those of you looking to get started with hacking on the JDK, there's a couple of things you need to do:

  1. Fetch the prereqs.
  2. Fetch the source through Mercurial.
  3. Set up your build prompt.
  4. Type "make" and go away for an hour or two.

Naturally, things are just a teeny bit more complicated than that, particularly if you're on a Windows box. (Update: Volker Simonis has blogged, similar to this post, his experience in configuring a Suse Enterprise Linux 9.3 box to build the OpenJDK.) Thus, as one who's labored through this process on said platform, I'll show you how I got it all up and running on my machine (well, technically, pseudo-machine, it's a VMWare image with Windows XP SP2 in it). If you have questions, you're free to send me email, but chances are I'll just redirect you to build-dev, where the amazing Kelly O'Hair hangs out and answers build questions. (MAJOR kudos again to Kelly for getting this done!)

Note that Sun is looking at other platforms, and has some good docs on building for Ubuntu 6.x and 7.x in the README already known--I've managed that with very little difficulty, so if you're starting from scratch, I'd suggest grabbing the free VMWare Player, an Ubuntu 7.04 Desktop image, and use that as a JDK build environment.

While we're at it, along the way, I'll be pointing out areas that I think Sun could use and would appreciate some community contributions. (People are always asking me this at conferences, as a way of making their name more well-known and building credibility in the industry.) Note that I have no "pull" with Sun and can't begin to guess where they want the help, I'm simply suggesting where I think the help would be useful--to the community if not to Sun directly.

By the way, the official document for build process requirements is the OpenJDK Build README; I only offer this up as a supplement and to offer up my own experiences. Note that I didn't go "all the way", in that I don't care about building the Java Plug-In or some of the other ancillary stuff, such as the JDK installer itself, so I didn't necessarily install all the bits documented on the OpenJDK README page. I wanted source that I could hack, step into, debug, and so on.

Without further ado....

1. Fetch the prereqs

This sort of goes without saying, but in order to build the JDK, you need to have the necessary tools in place.

  • Environment. The build needs to be portable across both Windows and *nix, obviously, so OpenJDK needs a *nix-like environment on the Windows platform. Originally, back in the JDK 1.2 era, this was a commercial toolkit Sun purchased, the MKS Toolkit, but obviously that doesn't work for open source, so they've chosen to use Cygwin. You'll need to make sure you have a couple of tools explicitly documented by Sun (ar.exe, cpio.exe, make.exe, file.exe, and m4.exe), but realistically you'll want the rest of the Cygwin developer tools just to have a complete environment. Cygwin afficionados will (hopefully) weigh in with what the best packages mix to grab are; I just grabbed everything that looked tasty at the time, including stuff that had nothing to do with building OpenJDK. Note that there is a big problem with the make.exe that comes with Cygwin, however...  (Update: Poonam's Weblog notes, "Along with the default installation, we need to install Devel, Interpreters and Utils packages.")
    • On my system, I put this in C:\Prg\cygwin.
    • CONTRIBUTION: There's a lot of MSYS developers who would love it if you could figure out how to make the build work with their toolchain, too.... and don't ask me how, because I have no real idea; I'm totally n00b when it comes to the differences between the two.
  • GNU Make 3.78.1 to 3.80. NOT the 3.81 or later version, because apparently there's problems with DOS-like paths, like C:/ (which is obviously going to be a factor on Windows; see some of Kelly's problems with shells for examples of what he's had to wrestle with). Getting this turned out to be a pain, and required some searching; Kelly pointed out a patched make.exe on Cygwin that should work. Make sure this make appears before the regular Cygwin make in your shell prompt (later). (Update: Find the right one here, as well.)
    • On my system, I created a directory for the OpenJDK project, in C:\Prg\OpenJDK, and put GNU make in C:\Prg\OpenJDK\bin.
    • CONTRIBUTION: Either fix the damn PATH issues ("Dear Mr. Gates, Would you please tell your developers to use the right kind of slash, already?"), or else fix Cygwin's make to recognize C:/ (note the forward slash) paths. Not sure what else could be done here.
  • Compiler. Sun originally was using the Microsoft Visual C++ 6.0 environment (which made sense at the time, since they were a company and could pay for it); with the open-source release... well... turns out that they're still using the Microsoft tools, only they've also added Microsoft Visual Studio 2003 to the list of supported compilers. (I'm using MSVS2003 myself.) This is a pain because both of those environments are commercial, and the Visual C++ 2005 Express (which is free) doesn't seem to work yet. People have suggested other compilers (Watcom's OpenC++, Cygwin's gcc, and so on), but right now that doesn't sound like a high priority for Sun. Of course, it's fair to suggest that if you're building for Windows, you probably have a MSVS installation somewhere, but still, it'd be nice....
    • On my system, I put MSVS2003 in C:\Prg\MSVS2003. Note that I *just* installed the Visual C++ bits, and left out the rest of the .NET stuff. (I do .NET in another VMWare image, so I don't need it here.) To make our life simpler, reister the environment variables globally. (This is an install option.)
    • CONTRIBUTION: Port the makefiles to use Visual C++ 2005 Express, or one of the other free compilers. I would think the easiest transition would be to VC2005Ex, but there may be some tools missing from the Express editions that the build needs; I haven't spent much time here researching what's working and not. This would likely be (much) harder for other compilers, owing to the differences in toolchains.
    • CONTRIBUTION: Port the makefiles to use Visual Studio 2008.
  • DirectX SDK. Yes, you need the DirectX SDK, specifically the Summer 2004 9.X Update, for building some of the advanced graphics stuff. The Build README has it linked there, as well, and the link, as of this writing, is still good. Install it, then take note of the DXSDK environment variable--we'll need it later.
    • On my system, I put DirectX in C:\Prg\DirectX9SDK_062005.
  • FreeType 2. This is something to do with fonts, and is needed to remove a commercial dependency that was holding up the OpenJDK from building about a year ago. Grab it, install it, and note the headers and lib directory. The FreeType download page has some links to pre-built stuff, but in the end, you just want freetype.dll, freetype.lib, and the various FreeType headers.
    • On my system, I put these in C:\Prg\OpenJDK\deps\freetype-igor (named after the helpful soul on build-dev who was kind enough to send me his pre-built FreeType bits). Note that underneath that directory, I have windows/freetype-i586/headers and /lib, which I'll use later for environment variables.
    • CONTRIBUTION: Put a "JDK-specific" bundle of FreeType somewhere on the Web for people to download and not have to build. :-)
  • A "bootstrap" JDK. Go grab JDK 1.6; you'll need this for building the Java bits. (I would hope this isn't a problem for you; if it is, you may want to quickly go to some other Web page. Any web page.)
    • On my system, this resides in C:\Prg\jdk1.6.0.
  • Apache Ant. At least version 1.6.3, I'm using 1.7 without a problem.
    • On my system, this resides in C:\Prg\apache-ant-1.7.0.
  • The "binary plugs". As much work has Sun has done to unencumber the JDK, there's still little bits and pieces that are commercial that they can't release the source to, so they put them into a "binary plugs" package and have you install it, then point to it in the build scripts, and copy those files over. They get versioned every time Sun releases a built JDK 7 bundle, but I don't think you need to grab this more than once; just the same, keep an eye on that as time goes on, and if you get weird build errors, check build-dev to see if the plugs changed.
    • On my system, this resides in C:\Prg\OpenJDK\deps\openjdk-binary-plugs. (The .jar file is an executable jar, so just "java -jar" it and tell it to install in C:\Prg\OpenJDK\deps; it adds the rest. It's done in 3 seconds, and consists of 1 file. Now you see why I wouldn't worry too much about this.)
  • Mercurial. This is a distributed revision control system, and there's lots more to say about that at the Mercurial website. Its commands look somewhat similar to SVN, though definitely read "Distributed Revision Control with Mercurial" if you're going to be keeping up with the source trees as they go. You *want* the "forest" extension as part of your Mercurial binary, so grab the "Batteries Included" installer version. I went with the non-TortoiseHG version, and had to download all four of the released files off that page and install and uninstall and install and uninstall until I found one that worked (the "win32extrasp1.exe" version in the "dec" release list on Sourceforge).
    • On my system, Mercurial lives in C:\Prg\Mercurial. Put in on the PATH so you have access to "hg.exe".
    • CONTRIBUTION: Figure out what the differences are and post it someplace--how to get the "forest" extension installed and turned on in Mercurial was a pain; Google was of little to no help here. (Tag it as a comment to this blog entry, if you like, and I'll update the entry itself once I see it.)
    • Update: Daniel Fuchs blogs about how to get Mercurial's "forest" extension installed in your installation, in case you don't get the "Batteries Included" version:

      I simply cloned the forest repository in c:\Mercurial. In a cygwin terminal:

        cd c:/Mercurial
        hg clone http://www.terminus.org/hg/hgforest  hgforest

      Then I edited c:/Mercurial/Mercurial.ini and added the lines:


      as documented in the Mercurial Wiki.

  • Optional: FindBugs. The build will start using FindBugs to do source-analysis to find bugs before they happen, so it's not a bad idea to have that as well.
    • On my system, this resides in C:\Prg\findbugs-1.2.1.

At this point, you should be ready to go.

2. Fetch the source.

Ivan's got it (mostly) right: just do this:

cd C:\Prg\OpenJDK

md jdk7

hg fclone http://hg.openjdk.java.net/jdk7/jdk7/ jdk7

(Don't use MASTER as he does, I don't think that works--that was just for the experimental repositories.) Don't forget the trailing slash, either, or you'll get an error saying something along the lines of http://hg.openjdk.java.net/jdk7%5Ccorba is not a valid URL or somesuch.

If your Mercurial doesn't have the "forest" extension, "fclone" won't work; Ivan's got tips on how to pull down the sub-repositories by hand, but I get nervous doing that because what if the list changes and I wasn't paying attention?

Your network will go wild for about twenty minutes or so, maybe longer, pulling lots of stuff down from the URL above. The sources should now reside in C:\Prg\OpenJDK\jdk7. Go browse 'em for a bit, if you feel so inclined. Get a good rush going, because this next step can be the tricky one.

Update: Volker Simonis ran into some issues with using Mercurial and an HTTP proxy, and found it difficult to find assistance across the Web. In the interests of making it easier for others, he's allowed me to republish his experience here:

I just had a real hard time to get the forest extension working and finally found out that it was because the forest extension doesn't honor the "http_proxy" environment variable. So I thought I'll post it here in case anybody else will face the same problem in order to save him some time. (If you're only interested in the solution of the problem, you can skip the next paragraphs and jump right to the end of this post).

I installed Mercurial and the forest extension as described in various places, here on the list and on the Web - that was the easy part:) Afterwards I could do:

/share/software/OpenJDK> hg clone http://hg.openjdk.java.net/jdk7/jdk7/ jdk7
requesting all changes
adding changesets
adding manifests 
adding file changes
added 2 changesets with 26 changes to 26 files
26 files updated, 0 files merged, 0 files removed, 0 files unresolved

So everything worked fine! Note that I'm behind a firewall, but Mercurial correctly picked up my http proxy from the "http_proxy" environment variable!

But now, everytime I tried 'fclone', I got the following error:

/share/software/OpenJDK> hg fclone http://hg.openjdk.java.net/jdk7/jdk7/ jdk7 
abort: error: Name or service not known

That was not amusing. First I thought I got something wrong during the installation of the forest extension. I than used the '--traceback' option to "hg" which told me that the error was in keepalive.py:

/share/software/OpenJDK> hg --traceback fclone http://hg.openjdk.java.net/jdk7/jdk7/ jdk7 
Traceback (most recent call last):
File "/share/software/Python-2.5.1_bin/lib/python2.5/site-packages/mercurial/keepalive.py", 
line 328, in _start_transaction raise urllib2.URLError(err)
URLError: <urlopen error (-2, 'Name or service not known')>
abort: error: Name or service not known 

So I enabled the debugging output in keepalive.py and realized, that the first two connections to hg.openjdk.java.net where made trough the proxy, while the third one (the first that actually fetches files), wants to go directly to hg.openjdk.java.net, which badly fails:

/share/software/OpenJDK> hg fclone http://hg.openjdk.java.net/jdk7/jdk7/ jdk7
keepalive.py - creating new connection to proxy:8080 (1078835788)
keepalive.py - STATUS: 200, OK
keepalive.py - re-using connection to proxy:8080 (1078835788)
keepalive.py - STATUS: 200, OK 
keepalive.py - creating new connection to hg.openjdk.java.net (1078970092)
abort: error: Name or service not known

The problem can be fixed by adding the proxy settings to your .hgrc file, like this:


where you have to replace "proxy:8080" with the name and the port of your real proxy host!

Volker's original email came from the buid-dev list, and if you have further questions about Mercrial and HTTP proxies, I'd suggest that as a resource.

3. Set up your environment.

This is where you'll spend a fair amount of time, because getting this right can be ugly. There's some environment variables that tell the build script where to find things, and we have to point out those things, like compiler location and such. If you installed everything in the same places I did, then the following, which I put into C:\Prg\OpenJDK\build_shell.sh, should work for you:


# "External" bits (outside of OpenJDK path structure)
export ALT_BOOTDIR=C:/Prg/jdk1.6.0
export ANT_HOME=c:/Prg/apache-ant-1.7.0
export FINDBUGS_HOME=/cygdrive/c/Prg/findbugs-1.2.1

# OpenJDK flag (to make FreeType check pass)
export OPENJDK=true

export OPENJDK_HOME=C:/Prg/OpenJDK
openjdkpath=$(cygpath --unix $OPENJDK_HOME)

# OpenJDK-related bits
# (ALT_JDK_IMPORT_PATH fixes a corba bug; remove it later)
export ALT_JDK_IMPORT_PATH=$(cygpath --unix C:/Prg/jdk1.6.0)
export ALT_BINARY_PLUGS_PATH=$OPENJDK_HOME/openjdk-binary-plugs
export ALT_FREETYPE_LIB_PATH=$OPENJDK_HOME/deps/freetype-igor/windows/freetype-i586/lib
export ALT_FREETYPE_HEADERS_PATH=$OPENJDK_HOME/deps/freetype-igor/windows/freetype-i586/include/freetype2
. $openjdkpath/jdk7/jdk/make/jdk_generic_profile.sh

# Need GNU make in front of Cygwin's; this is the only practical way to do it
export PATH

# Let people know this is an OpenJDK-savvy prompt
export PS1='OpenJDK:\[\e]0;\w\a\]\[\e[32m\]\u@${COMPUTERNAME}:\[\e[33m\]\w\[\e[0m\]\n\$ '

Note the UNICOWS_DLL thing in the middle; this was necessary in earlier builds, and I don't know if it still is. For now I'm not messing with it; if you discover that you need it, the Build README has links. (Update: Kelly confirmed that this is no longer necessary in the OpenJDK build. Yay!)

Note that I set the COMPILER_VERSION flag to tell the build script which compiler I'm using--if that's not set, the build fails pretty quickly, complaining that "COMPILER_VERSION" cannot be empty. (Update: Kelly mentions, "I suspect the reason you are having the COMPILER_VERSION problem is that the makefiles are trying to run cl.exe to get the version, and if the PATH/LIB/INCLUDE env variables are not setup right, cl.exe fails. Several people have run into that problem.")

Note that OPENJDK must be set, or the build process thinks this is a commercial build, and an early sanity-check to see what version of FreeType is running will fail. (Specfically, Sun builds a tool just to see if the code compiles; if it fails to compile, chances are you forgot to set this flag. That's been my problem, each and every time I tried to rebuild the OpenJDK build space. Hopefully I never forget it again.)

Note that I call into jdk_generic_profile.sh to do some more setup work; this gets all the MSVS2003 stuff into the PATH as well.

Be very careful with which path you use; sometimes the build wants C:/Prg style paths, and sometimes it wants /cygdrive/c/Prg style paths. Don't assume the script above is perfect--I'm still testing it, and will update this entry as necessary as I find bugs in it.

(Update: Kelly mentions, "Be careful putting cygwin before VS2003 in the PATH, cygwin has a link.exe and so does VS2003, you need the one from VS2003.")

From a Cygwin bash prompt,

cd /cygdrive/c/Prg/OpenJDK

. ./build_shell.sh

cd jdk7

make sanity

It will churn, think, text will go flying by, and you will (hopefully) see "Sanity check passed". If not, look at the (voluminous) output to figure out what paths are wrong, and correct them. Note that certain paths may be reported as warnings and yet the buld will still succeed, that's OK, as far as I can tell.

And no, I don't know what all of those environment variables are for. Kelly might, but I suspect there's a lot of built-up cruft from over the years that they'd like to start paring down. Let's hope.

4. Type "make" and go away for a while.

Specifically, type "make help" to see the list of targets.

$ make help
Makefile for the JDK builds (all the JDK).

--- Common Targets ---
all -- build the core JDK (default target)
help -- Print out help information
check -- Check make variable values for correctness
sanity -- Perform detailed sanity checks on system and settings
fastdebug_build -- build the core JDK in 'fastdebug' mode (-g -O)
debug_build -- build the core JDK in 'debug' mode (-g)
clean -- remove all built and imported files
clobber -- same as clean

--- Common Variables ---
ALT_OUTPUTDIR - Output directory
ALT_PARALLEL_COMPILE_JOBS - Solaris/Linux parallel compile run count
ALT_SLASH_JAVA - Root of all build tools, e.g. /java or J:
ALT_BOOTDIR - JDK used to boot the build
ALT_JDK_IMPORT_PATH - JDK used to import components of the build
ALT_COMPILER_PATH - Compiler install directory
ALT_CACERTS_FILE - Location of certificates file
ALT_DEVTOOLS_PATH - Directory containing zip and gnumake
ALT_DXSDK_PATH - Root directory of DirectX SDK
ALT_MSDEVTOOLS_PATH - Root directory of VC++ tools (e.g. rc.exe)
ALT_MSVCRT_DLL_PATH - Directory containing mscvrt.dll
WARNING: SLASH_JAVA does not exist, try make sanity
WARNING: CACERTS_FILE does not exist, try make sanity

--- Notes ---
- All builds use same output directory unless overridden with
ALT_OUTPUTDIR=<dir>, changing from product to fastdebug you may want
to use the clean target first.
- JDK_IMPORT_PATH must refer to a compatible build, not all past promoted
builds or previous release JDK builds will work.
- The fastest builds have been when the sources and the BOOTDIR are on
local disk.

--- Examples ---
make fastdebug_build
make ALT_OUTPUTDIR=/tmp/foobar all
make ALT_OUTPUTDIR=/tmp/foobar fastdebug_build
make ALT_OUTPUTDIR=/tmp/foobar all
make ALT_BOOTDIR=/opt/java/jdk1.5.0
make ALT_JDK_IMPORT_PATH=/opt/java/jdk1.6.0


The one I want is "make fastdebug_build" or "make debug_build" (so I have debug symbols and can go spelunking). Do it.

Watch the stuff go flying by.

Get bored.

Get lunch.

Come back, it might be done. :-)

If it's a successful build, you'll have "stuff" in the C:\Prg\OpenJDK\jdk7\build directory, corresponding to the kind of build you kicked off; for a "fastdebug" build, for example, there'll be a "windows-i586-fastdebug" directory in which you'll find a "j2sdk-image" directory in which there should be a complete JDK environment. Try running Java and see if it works (make sure your PATH is updated to point to the right place before you do!)

If not, it's debugging time. :-) Note that the "build" directory is completely built from scratch, so if you get a partial build and want to start over from scratch, just "rd /s build" from the jdk7 directory. (It's easier than "make clean" or "make clobber", I've found.)

More About Builds

When building the JDK, you may want to build bits "underneath" the top-level directory, but doing this is a tad tricky. I asked about this on the build-dev list, and Kelly responded with a great email about the build process, specifically about launching "sub" makes within the system:

Due to history, a build directly from the jdk/make directories uses a default OUTPUTDIR of jdk/build/* but if FASTDEBUG=true, it's jdk/build/*-fastdebug, or if a plain debug build with just VARIANT=DBG it would be jdk/build/*-debug The variant builds leave results in a completely separate outputdir.

If you used the very top level makefile (which came from the now defunct control/make area) the default OUTPUTDIR is ./build/* (at the very top of the repositories). When this top level Makefile runs the jdk/make Makefiles, it passes in a ALT_OUTPUTDIR to refer to this top level build result area because it's default outputdir is not the same place.

I don't know the complete history as to why this was done this way, but my tendency is to try and get us back to a single default OUTPUTDIR for all the repositories. Someday...

This is what I do when I work on just the jdk repository:
cd jdk/make && gnumake

That primes the outputdir area, then I can drop down in:
cd jdk/make/java && gnumake

Or even drop in and clean an area and re-build it:
cd jdk/make/jpda && gnumake clean && gnumake

Or just repeat the entire build (incremental build)
cd jdk/make && gnumake

If I wanted the jdk image (j2sdk-image), I would need to:
cd jdk/make && gnumake image

But the output by default will go to jdk/build/* and a different directory if VARIANT=DBG or FASTDEBUG=true.

This should help having to go through the whole process for incremental updates. (Note that on my system, I had to call it "make" instead of "gnumake".)


As time goes on, I'll hopefully find the time to blog about how to find various little things in the JDK and make source-modifications to prove that they work, and use that as a springboard from which to let you start hacking on the JDK. In the meantime, please, if you run into trouble and find fixes to any of the above, comment or email me, and I'll correct this.

Contributions/Suggested TODOs

  • Have the make system automatically capture the results of the build in a log file, for easier debugging. Granted, you can "make >| build.output", but that seems tedious when it could easily be captured automagically for you each time. ("make sanity" does this, capturing the results in build/windows-i586-fastdebug/sanityCheckMessages.txt and sanityCheckWarnings.txt.
  • Documentation, documentation, documentation. This thing does a lot of recursive makes and invokes a lot of tools (some of them built as part of the build process itself), and it would be much easier to debug and understand if the process were better documented. Even a simple flowchart/tree of the various Make invocations and what each does (in practice) would be helpful when trying to track down issues.
  • Add support for all output to be captured into a build log file. This can obviously be done at the command-line via "make |& tee build.log" or ">& build.log", but I think it'd be nice if it were somehow folded in as part of the build process so it happened automatically.


  1. Kelly OHair sent me some updated information, such as the right link to use for the README file (from the HG repository instead of the SVN one).
  2. Kelly also mentioned that the plugin and installers are not part of the OpenJDK build yet, so that's not something I could build even if I wanted to. Which is fine, for me. :-)
  3. Kelly confirmed that UNICOWS is not needed in OpenJDK.
  4. Kelly mentions that link.exe on the PATH must be VS2003's, not Cygwin's.
  5. Kelly mentions the COMPILER_VERSION problem might be PATH issues.
  6. Kelly notes, "On the C:\ vs C:/ vs. /cyg*/ paths, I try and use the C:/ all the time everywhere, and anywhere in the Makefiles where I know I need C:\ or the /cyg*/ paths, I try and use cygpath or MKS dosname to force them into the right form. NMAKE.EXE only likes C:\ paths, and cygwin PATH only wants /cyg*/ paths, and Windows/Java/MKS never want /cyg*/ paths. :^( I wish we had a better solution on Windows for this shell/path mania."
  7. Poonam's Weblog has a good page on building the OpenJDK on Windows with NetBeans, from which I've stolen... ahem, leveraged... some links. His webpage has a link for the UNICOWS download page, but that only includes the DLL, not the .LIB, which you will also need. (It's an import library for the DLL; you need both.) The only place I know to get the .LIB is from the Platform SDK, and you need an old one, circa November 2001 or so. I don't know if it's kosher to redistribute any other way (meaning, Microsoft won't let us, as far as I know).
  8. Added Volker Simonis' experiences with HTTP proxies in Mercurial
  9. Added the "sub" make build discussion from Kelly on build-dev
  10. Added the link to Volker's blog about building on Suse Linux