Re: [Qemu-devel] harddrives and QEMU

[Karl Magdsick <kmagnum@gmail.com>]

> >
> Alright, but here's the rub. If a drive can be booted by a machine. Why
> can't it boot from Qemu if it's accessing the raw disk via the windows
> interface? This needs no messing with bios or disksize to boot of a
> regular machine.
>

I hope someone else will chime in, but my guess is that the problem
lies in that an MS Windows "drive" is really a partition, not the entire
drive. Under Windows you're specifying the equivalent of
the Linux /dev/hda1 , /dev/hda2, /dev/hdb1, /dev/hdb5 and not
actually /dev/hda or /dev/hdb.

In other words, to QEMU it looks like the drive got chopped off at some
point.  All of the data before a certain point and after another point on
the HD is simply missing (and the indexing is incorrect if a non-zero number
of bytes have been chopped from the beginning of the disk).

I'm not sure if MS Windows includes the MBR in the first drive on the disk.

In order to pass the "D drive" to qemu, and actually give QEMU access
to the entire raw HD, the "D drive" partition would have to fill the entire
HD, and MS Windows would have to make the MBR available as part
of the first (only, in this case) partition on the HD.

Presumably, you'd like QEMU to make up a fake partition table/MBR
to present to the guest OS so that the guest OS sees a self-consistent
disk.



-Karl