11:51 a.m.
I'm using a Windows raw disk image that is "converted" to the VDI
format by custom code that prepends a header to the image.
I use 'vdi' for GUESTFS_ADD_DRIVE_OPTS_FORMAT of
guestfs_add_drive_opts().
After launching the appliance, the call to guestfs_list_partitions()
results in an empty list.
Is there a way to add the drive but have an offset into the image
file as a "starting point"?
So that it could skip the header which apparently is causing the
issue.
If I use the image without the vdi customization (and use 'raw' for
add_drive_opts) then list_partitions is successful.
4:38 p.m.
On Thu, Mar 14, 2013 at 12:51:10PM -0400, Skippy VonDrake wrote:
I'm using a Windows raw disk image that is "converted"
to the VDI
format by custom code that prepends a header to the image.
I use 'vdi' for GUESTFS_ADD_DRIVE_OPTS_FORMAT of
guestfs_add_drive_opts().
After launching the appliance, the call to guestfs_list_partitions()
results in an empty list.
Is there a way to add the drive but have an offset into the image
file as a "starting point"?
So that it could skip the header which apparently is causing the
issue.
Essentially libguestfs can do whatever qemu can do. In this case it
seems as if qemu can't recognize the "vdi" image, nor (looking at the
qemu man page) does it seem that qemu is able to use an offset into an
image.
You'd have to add this feature to qemu, which is probably a simple
enough patch if you know what to do.
The other alternative would be some sort of Linux layer that can
modify offsets in images, eg. something using FUSE or an LD_PRELOAD
library.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
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7:40 a.m.
I accidentally found a way to do this using qemu-nbd. It's
not tested, but something like this should work:
qemu-nbd disk.img -o <offset> -t
qemu-img create -f qcow2 -b nbd:localhost:10809 /tmp/overlay
# and then run libguestfs as normal on /tmp/overlay
This is read-only (because of the overlay). However at the moment I'm
adding direct nbd support to libguestfs, so once committed it will be
able to access nbd exports in write mode.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Fedora Windows cross-compiler. Compile Windows programs, test, and
build Windows installers. Over 100 libraries supported.
http://fedoraproject.org/wiki/MinGW
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participants (2)
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Richard W.M. Jones -
Skippy VonDrake