[Qemu-devel] booting from /dev/hd?

[Tim <tim-qemu@sentinelchicken.org>]

Hello,

I know it is considered dangerous, but I am willing to accept the
risk...  Has anyone been able to boot a virtual machine from their main
boot drive while the drive is in use?

More specifically, I have a dual boot system, win2k/debian, and I would
like to try booting windoze from this disk as a guest OS while running
the linux system from this same disk.  In order to protect my disk from
erroneous writes, I planned on running the vm system with -snapshot.

I have tried this, and with basic options:

qemu -hda /dev/hda -snapshot -boot c

my bootloader (grub) comes up just fine, but once I select win2k, it
reports a disk read error.  When booting Debian, it loads the kernel and
tries to begin booting, but just hangs.  This may be because my kernel
is customized for my Athlon though...  
I figured the windoze issue might be a geometry problem, so I ran 
`fdisk -l /dev/hda' and then used that geometry:

qemu -hda /dev/hda -snapshot -boot c -hdachs 4865,255,63

and I get the same results.  Perhaps I need to use a non-LBA geometry or
something?  I really don't know much about disk geometry, just a
guess...


Has anyone tried doing something similar to what I am attempting?  If
so, did you have any success, and what did you try that I haven't?  I am
pretty sure I have permissions right in the host OS, is there anything I
am forgetting?

thanks,
tim