Comment # 8 on bug 1003999 from Olaf Hering

Beside the missing frontend drivers, how did that /dev/dm-N work for KVM
guests? Was that just a special raw filesystem/swap for Xen guests?

After changes made for bug #979002 a guest can now convert a domU.cfg 'hda'
entry into a symlink to xvda. This is done in xen-tools-domU.

However, this case is not covered because the rule considers only disk names:
/usr/lib/udev/rules.d/60-persistent-xvd.rules
KERNEL=="xvd*[!0-9]", ENV{VBD_HD_SYMLINK}=="hd[a-d]",
SYMLINK+="$env{VBD_HD_SYMLINK}"

As we discovered, hda2 used to work because the xenlinux based blkfront driver
tried to claim the name from the config file (hda2) in the guest and provide a
device node 'hda2' with major:minor 3:2.
This does not work anymore with pvops, it always uses xvd* als namespace.
However, a udevrule can be used to create a compat symlink. Looks like the rule
has to be extended to cover also hd?[0-9]*