I got myself one of the fancy shmancy netbooks. Due to a habit and some hardware issues I needed to compile a kernel. The problem here though is that it takes for ever to build a kernel on one of these things. No sweat I'll just build it on my desktop, it'll only take 5-10 minutes. But of course there is a catch. My desktop is 64bit and this new machine is an Atom CPU which only does 32bit.

The process for compiling a 32bit kernel on a 64bit machine is probably a lot easier if you don't compile it the Debian way. But this is not something I want to do, I like installing the kernels through the package manager and doing this type of cross compile using make-kpkg is not trivial. There are plenty of forum and email threads about people recommending to use chroot or virtual machines for this task, but that is such a chore to set up. So here is my recipe for cross compiling 32bit kernel on 64bit host without chroot / vm, the-debian-way.

1. Install 32bit tools (ia32-libs, lib32gcc1, lib32ncurses5, libc6-i386, util-linux, maybe some other ones)
2. Download & unpack your kernel sources
3. run "linux32 make menuconfig" and configure your kernel for your new machine
4. clean your build dirs "make-kpkg clean --cross-compile - --arch=i386" (only needed on consecutive compiles)
5. compile your kernel "nice -n 100 fakeroot linux32 make-kpkg --cross-compile - --arch=i386 --revision=05test kernel_image" for faster compilation on multi-CPU machines run "export CONCURRENCY_LEVEL=$((cat /proc/cpuinfo |grep "^processor"|wc -l*2))" first
6. At this point you have a 32bit kernel inside a package labeled for 64bit arch. We need to fix this, run "fakeroot deb-reversion -k bash ../linux-image-2.6.35.3_05test_amd64.deb". Open the file DEBIAN/control with vim/emacs and change "Architecture: amd64" to "Architecture: i386" exit the bash process with ctrl+d
7. That's it, now just transfer the re-generated deb to destination machine and install it.

Many if not all ideas for this process come from reading email threads the comments made by Goswin Von Brederlow were particularly helpful, thanks.