The attached patch allows the md driver to be built as a module, and
still use the raidautorun feature (basically, using RAID partition
tagging (0xfd) and persistent RAID superblocks to autorun detected
arrays at boot time). This was previously not possible. In the process,
the patch also cleans up some unnecessary, and ugly, interdependencies
between the partitioning code and the md driver. 

The patch should allow vendors to compile md as a module (saving roughly
50k in their default kernel images) without any loss in functionality.
It would also allow other volume managers to use the RAID partition
tagging to autodetect arrays (if desired).

This patch has been tested for several days against 2.5.67/68 with an
md/RAID5 root partition, which gets autorun at boot time (in the
initrd). 

Feedback welcome. Please test, if you're interested. If the patch looks
good, please apply.


Thanks,
Paul


P.S., If anyone is interested, I've also got a patch for UnitedLinux
mk_initrd to make it work properly with modular md and the 2.5 kernel
(look for .ko modules, etc.).