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How to handle kernels of the same version
I've known for a while now, but just now had a chance to implement, how to
handle several kernels of the same version, while maintaining the ability
to use modules. It's a simple concept really, and a very simple
The basic concept is to use the kernel version number (rather than the
kernel version) to index the modules. Every kernel is built using a
version number, the previous kernel having been built with the number
stored in /usr/src/linux/.version. This it the value you see when you do a
Linux psi.int.omegacs.net 2.0.32 #1 Sun Nov 30 15:34:00 PST 1997 i586 unknown
Since /etc/conf.modules can specify paths to the modules directories, and
since they are passed through a shell for expansion, as per the
documentation, we can not only specify the kernel version, but the version
path=/lib/modules/`uname -r`-`uname -v | cut -c2- | cut -d\ -f1`
There are quite a number of paths to set, including that of every
subdirectory (block, cdrom, fs, ipv4, misc, net, pcmcia, scsi), and the
path to the modules.dep file.
However, once these are set up properly, you can boot to any kernel you
want, as long as you have the modules in the right place (i.e.
/lib/modules/2.0.30-2), and the kernel actually matches those modules.
In order for the modules to stay in sync, however, we'll have to be very
careful with the .version file. The kernel Makefile will automatically
increment it by one during a build of zImage, so as long as we find the max
of the existing kernel version numbers on the current system and put that
in .version before building, we should be OK.
If anyone has a machine to play around with this on, see if you can come up
with some scripts to handle setting the .version file correctly, building a
kernel, and installing everything in the right place. For now you can
assume that you're being given a correct .config file.
Erik Walthinsen <email@example.com> - SEUL Project system architect
/ \ SEUL: Simple End-User Linux -
| | M E G A Creating a Linux distribution
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