Booting same NetBSD install native, as dom0 and domu

[Joachim König <him%online.de@localhost>]

Hello,

I have 3 OSs installed on my notebook:

- NetBSD-current
- Debian Lenny
- Windows XP

I'd like to achieve the following:

- boot NetBSD or Debian either native or dom0 and in
  the latter case boot the other as domu and Windows
  XP as hvm.

Booting the same NetBSD or Debian installation native or as dom0
is not a problem as this is supported out of the box for each of them,
with either grub or in the case of NetBSD even with the NetBSD boot
loader.

Booting such a Debian installation as domu under NetBSD is also not
a big issue, because the disk, exported by the NetBSD dom0 to the
Debian domu is seen there as a standard disk, e.g. sda or hda.

Booting NetBSD as domu under a Debian dom0 is however more difficult
as the disk exported by the Debian dom0 is seen as xbd0 whereas it is
seen as wd0 (or sd0) when NetBSD is booted as dom0 or native.

This unfortunately requires a different /etc/fstab which I'd like to
avoid.

Of course there are workarounds, e.g. copying the root filesystem and
booting the copy with the modified /etc/fstab, but this requires constant
mirroring of the root fs copy when updating NetBSD.

The other slight differences required to boot a NetBSD installation as
domu described in a number of howtos like changes to /etc/ttys or the
different network interface name can/could be handled gracefully easily,
but for fstab it's not easy:

- the path is hardcoded in fstab.h as _PATH_FSTAB and used in a number of
  places
- the entry for the root filesystem must be already correct before the 
filesystem
  is mounted r/w so it cannot be modifyed early during boot.

Any ideas how I could achieve booting the same NetBSD install as 
domu/dom0 and how
to solve the fstab issue?

Joachim