amd64 kernel on i386 sarge system

[Brendan Hack]

Hi,   We recently setup up an i386 Sarge fileserver on a dual opteron system (unfortunately I did not setup this system up myself so am not entirely familiar with how it was done). As part of the install process sarge installed the kernel from the kernel-image-2.6.8-11-amd64-k8-smp package. Uname –a gives the following:   Linux server01 2.6.8-11-amd64-k8-smp #1 SMP Mon May 30 20:47:11 UTC 2005 x86_64 GNU/Linux   This setup has been working fine however I’ve recently run into a problem. I need to install some 3rd party, closed source, kernel modules (yeah, yeah, I know) and unfortunately these don’t support x86_64 kernels, only 32 bit. Since this is a vital production fileserver which is in heavy use I’m a bit reluctant to just install a stock i386 kernel image (eg: kernel-image-2.6.8-2-k7-smp) in case I cause some serious problems. Can someone please ease my mind and let me know how safe it is to switch kernels like this. I have plenty of experience messing around with kernels, compiling my own and setting up systems which boot to different kernel versions so can set this up no problems but just want to make sure that I won’t have any compatibility issues when downgrading from the amd64 kernel to the k7. Can anyone see any issues with doing this?   One other problem I ran into while investigating this issue was that this setup (amd64 kernel in an i386 sarge environment, which is the one installed by default on this system) it is not possible to compile your own kernel with the supplied tools. The gcc 3.3.5 which comes in sarge does not support compiling to amd64 and even when I installed the gcc 3.4 package and compiled with -m64 the linker was unable to find the gcc_s_64 library. I have installed the amd64-libs-dev package. I find it very strange (and frustrating) that the default debian installer can install a system where it isn’t possible to easily recompile a kernel.     Thanks for any help   Brendan