Comment # 9 on bug 906990 from Lukas Ocilka

(In reply to Ulrich Windl from comment #4)
> GRUB2 definitely _can_ detect operating systems, and YaST detects Linux
> installations as part of the upgrade function. YaST also knows how to
> install the bootloader.

Just a side note: Yast needs libstorage to detect available partitions.
The Upgrade then mounts partitions one by one and searches for some
SUSE Linux identifiers (they have changed since this functionality has been 
implemented). Yast, for sure, knows how to install bootloader and also
includes kexec functionality - all that in very different pieces of code
(and different RPMs). BTW, kexec did not work in all cases.

All this (libstorage init, mounting partitions, detecting systems,
bootloader initialization, ...) takes a lot of time and you definitely
don't want Linuxrc (to call Yast) to do it every time you boot from DVD.
Linuxrc and Yast are, of course, also different pieces of code.

Additionall, I do not think THIS should be supported on S390 (or other
systems with the possibility of hundreds or more disks attached).