[arch-general] Reboot - Versioned Kernel Installs

[Heiko Baums]

Am Fri, 10 Jun 2011 12:48:57 +0200
schrieb Vic Demuzere <vic at demuzere.be>:

> Having multiple kernels is insane. I don't get why it's needed. There
> is a live cd to rescue your system if needed.

And the old kernel packages (every package) are saved in pacman's cache
(usually /var/cache/pacman/pkg) anyway until pacman -Sc or pacman -Scc
is run. So every package can easily be downgraded by running pacman
-U /var/cache/pacman/pkg/<package-file-name>.

Of course, the pacman cache should only be flushed if the updated
software is working correctly.

There's no need for keeping old kernel images, even less included in a
new and updated kernel image or initrd, however this would be possible
anyway.

Maybe there could be made an option in /etc/pacman.conf for the kernel
package (a hook isn't needed) which tells pacman if it shall
first copy /boot/vmlinuz26 to /boot/vmlinuz26.old. But this should
definitely not be done by default for every user. And it's really not
necessary to backup all old modules for being able to boot an old
kernel for fixing the new one (see pacman -U above).

The better and much cleaner solution is to first try the fallback initrd
or to install a different kernel package like kernel26-lts parallel to
kernel26.

Keep in mind, those cases in which an updated kernel is unbootable
are very, very rare.

And people who need a reliable system and are so afraid of
broken kernels, of course, shouldn't use [testing]. They should better
install a multiboot system with one stable system and one test system.
This way they can test kernel updates from [testing] on their test
system and update the kernel on their stable system only if the test
system is working correctly. This would, btw., help to filing bug
reports for the kernels on esoteric hardware before they get into
[core].

Heiko