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ARCH="x84_64" make HOSTCC="gcc -m32" CC="gcc -m64" LD="ld -m elf_x86_64" bzImage ARCH="x86_64" make HOSTCC="gcc -m32" CC="gcc -m64" LD="ld -m elf_x86_64" bzImage

The FAQ below seems to be horribly out of date and still talks about the obsolete biarch that has been superseeded by a much cleaner [http://somewhere/ multiarch proposal]. I gave up reading halfway down the list without finding any reusable Q&A and gave up on it.

Please refer to the [https://alioth.debian.org/docman/view.php/30192/21/debian-amd64-howto.html wiki:?HowTo Debian amd64] for a more up-to-date manual.

Well, I think we should give it a new start. So I have tried to find the relevant Q&As, and deleted the rest:

The Debian on Amd64 FAQ

   This page holds the frequently asked questions regarding 
   the Debian port to ["AMD64"].

   If there are unanswered questions the best thing you can do is 
   to add the Q's at the bottom of this page.


Q: Is this port only for AMD-["CPUs"]?

A: No. "amd64" is the name chosen by AMD for the 64 bit architecture. Of course Intel does not want to use this name, so they call it x86_64 or ["EMT64"]. The architecture is still the same, and Debian amd64 will run on AMD and Intel x86 processors with 64bit support. In honor of the inventor AMD, Debian uses the name amd64.


Q: What distribution should I use? pure64, biarch, gcc-3.4?

A: If you want stability, use the 32bit version of Debian. A 64bit is cooler and a bit faster, but not nearly as "smooth". If you want 64bit, have a look at http://debian-amd64.alioth.debian.org/.


Q: Ok, so there is pure64, biarch, gcc-3.4 and more. Which one is the right one?

A: Short answer: use pure64.

Long answer: The problem is that 64bit programs require 64bit libraries, while 32bit programs require 32bit libraries, but there is only one standard place for the libraries.

pure64 is a clean port, and it uses only 64bit libraries. pure64 does not run 32bit programs (in general), so there will be no Flash and no Openoffice. See below for workarounds.

biarch is an old port, that followed the layout of the other 64bit architectures like ["SPARC64"]: libraries are split into /lib (for 32bit) and /lib64. This is also used by RedHat and Suse for their amd64 version, because you can still install and run old 32bit programs. However, conceptually it is a mess, because every library package has to be edited in order to compile a 64bit version.

gcc-3.4 is a port based on a new compiler version, which is now an experimental prerelease of gcc-4.0. This is supposed to be faster and better suited for multiarch, but it may not be as stable.

You should not mix these distributions.


Q: Ok, so how do I run openoffice?

A: Openoffice does not compile on a 64bit system. There are two alternatives, a clean (and difficult) one and a simple, but slightly messy one. The clean one is to install a 32bit system in a chroot environment. There are many ways to do that, the HOWTO covers some of them. If you already have a 32bit installation, you can (re-)use it for the chroot environment. You probably need to mount /proc and /tmp in the chroot environment.

You can also use the packages in http://debian-amd64.alioth.debian.org/openoffice.org/. They install the necessary 32bit libraries and a 32bit version of openoffice in /emul. Works for me (after adding a few more libraries).


Q: Wine does not work?

A: Yes, it seems that wine has problems on recent kernels (especially 2.6.10), and it also has issues with 64bit kernels. In theory, it should work. But it did not for me.


Q: Where is partimage?

A: Seems like partimage is not written to work on 64bit system. You may be able to use a 32bit binary. You can also resort of dump*fs, xfsdump, ntfsclone etc.


Q: And flash?

A: Same story: it is a 32bit binary, so you need a 32bit system and a 32bit browser. Personally, I do not want to loose the performance gain of a 64bit browser only to be able to play anoying ads, but there may be better reasons for flash.


Q: How do I install 64bit modules using 32bit userspace?

A: Refer to: http://url.raw.no/?628 . It includes a patch for both the kernel and the modutils which you need to apply.


Q: Where is memtest for ["AMD64"]?

A: Use the 32bit version, it works. All you need is the image memtest86.bin.


Q: How do I build i386 debs on amd64?

A: use the linux32 command to fake uname and limit memory size inside your i386 chroot. Package is linux32.

The following solution is based on the [https://alioth.debian.org/docman/view.php/30192/21/debian-amd64-howto.html#id274383 Debian-["AMD64"] Howto 'Running applications inside the chroot' Section].

Simplest way to build i386 packages out of the box on amd64 is to use dchroot and a simple wrapper script like the following example for dpkg-buildpackage:

   #!/bin/sh
   rpath=`pwd`
   dchroot -c i386 "cd $rpath && linux32 dpkg-buildpackage -ai386 $@"

Save it under /usr/local/bin/ia32-dpkg-buildpackage, make it executable and change the chroot name according to your environment.

You need to have your home directory available under the chroot.

Now you can build i386 packages using ia32-dpkg-buildpackage like dpkg-buildpackage. for example:

   $ ia32-dpkg-buildpackage -rfakeroot

remind to install the build-depends for the package inside the chroot.


Q: Is there a quick rundown on the changes you've made to apt/dpkg command-line syntax anywhere?

A: There are two new scripts that were added to dpkg.

dpkg-libinfo was added by Gerhard Tonn. It's intended use was in the s390x and sparc64 ports. It allows debian/rules files to figure out if /lib or /lib64 should be used. See --help, or usage of it in zlib.

dpkg-subarchitecture was added by Bart Trojanowski. The main goal of this is to allow for concurrent instalation of packages that were compiled for different CPU types, but can be executed on the local host. As you may already know, on amd64 hardware you can install and run software compiled for k8, k7, i686, i586, i486 and i386. That relationship is captured in the ls /usr/share/dpkg/subarchtable; or see http://www.jukie.net/~bart/debian/amd64/files/dpkg/subarchtable. Note that this feature can also be used to build i686 optimized modules.

Along with that the dpkg architecture was changed to 'amd64'. This means that package names built in 64bit are named *_amd64.deb, while 32bit binaries can be installed from the i386 distribution of Debian.

Apt's sources.list has a new feature too. You can specify what architecture apt should pull in from a given distribution mirror. Below is an example that would instruct apt to use the binary-i386 part of the testing distribution. If the (i386) is ommited then the default binary-amd64 would be used.

  deb http://ftp.debian.org/debian/ testing(i386) main non-free contrib

In addition apt now uses dpkg-subarchitecture script to determine if certain packages are subarchitectures of amd64. The -s flag requests a list of compatible architectures that can be installed. The actual call that apt makes is:

  $ dpkg-subarchitecture -s -aamd64
  i686 i586 i486 i386 all

There are a few other features that will still go into apt and dpkg. The next one that is requested is the test of library ABI. Basically binaries of any architecture and depend on applications of any other architecture, but for binaries that depend on libraries apt would have to make sure that the ABI is compatible. That is an i386 and i686 package has compatible ABI, but amd64 and ia64 do not. Again this is captured in the subarchtable file mentioned above.


Q: How do I port a debian package to amd64?

A: There should be no porting necessary, so just use the standard commands:

  apt-get source package
  cd package-version
  dpkg-buildpackage

If everything works out you will have a package-version_amd64.deb generated.


Q: Ok, so what do I have to do to port a library package to amd64?

A: With biarch, that used to be a pain, but with pure64 it should be no different from an ordinary package.


Q: How do I build my first amd64 binaries?

A: With pure64, it is a simple as gcc hello.c. gcc will automatically target a 64bit system. You can add -m32 to get a 32bit executable.


Q: Lots of us don't care about 32-bit compatibility, we don't run anything proprietary. We just want a native 64-bit port. Shouldn't that be simple to put together?

A: Yes, and that is what pure64 gives you.


Q: How do I bootstrap myself in 64 bits:

A: There are many ways. You can just download the installer and created a new 64bit installation. You can also use debootstrap from a running system. Remember that you need a 64bit kernel for a 64bit system. Using the 64bit kernel for a 32bit system may work, but there will probably be problems with loadable modules.

Or you can recompile the system yourself:

following the debian-amd64-howto, I have found the following differences: when compiling the kernel I had to 1) remove the ARCH:= line from the makefile and 2) use the command ARCH="x86_64" make HOSTCC="gcc -m32" CC="gcc -m64" LD="ld -m elf_x86_64" bzImage

Note: when using an MSI SCSI board, compile the kernel with SCSI and SCSI_DEV and MPT FUSION