Mounting a qemu created root disk image

Valhalla · 10-26-2005, 06:07 PM

I'm planning on installing Windows using qemu, since there are a few programs that require it, and it bothers me always having to reboot. Anyway, I was wondering, if I have windows format my disk image as FAT, will I be able to mount the disk image as a loopback device while qemu is not running?

cs-cam · 10-26-2005, 07:20 PM

Maybe. It'd depend what format you had qemu make the image (not filesystem, image format). Qemu can run from ISO files and they can be mounted as loopbacks so I guess it could be possible.

madluther · 10-26-2005, 09:06 PM

Its is possible if your disk image is in raw format.

as root run fdisk on your raw image file

Code:

fdisk -l win2k2.img

this should produce something like this

Code:

Disk win2k2.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
win2k2.img1   *           1        1304    10474348+   c  W95 FAT32 (LBA)
Partition 1 has different physical/logical endings:
     phys=(1023, 254, 63) logical=(1303, 254, 63)

The file system usually starts at track 1. You can mount it by using the offset option in losetup
The offset is one track or 63 sectors * 512 = 32256 bytes

Code:

losetup -o 32256 /dev/loop0 win2k2.img
mount /dev/loop0 /mnt

HTH

Mad.

Valhalla · 10-26-2005, 09:26 PM

So this is what I get from fdisk -l

Code:

You must set cylinders.
You can do this from the extra functions menu.

Disk c.block: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start         End      Blocks   Id  System
c.block1   *           1         636     5108638+   b  W95 FAT32

But it automatically always starts at 1 track from the start?

madluther · 10-26-2005, 09:34 PM

Yes, so use the same offset 32256