We've had requests from products that use libguestfs & virt-v2v to
provide additional tooling for:
(a) Inspecting a virtual machine disk image to find out what virtual
devices it needs (ie. what drivers are installed in the guest).
(b) Taking a Windows disk image and injecting virtio drivers from the
virtio-win suite.
Virt-v2v does both operations as a part of importing guests from
VMware to KVM, but it doesn't expose these as separate operations.
- - -
For (a), you might run the tool against a disk image and it would
display various facts (similar to virt-inspector
https://libguestfs.org/virt-inspector.1.html):
$ virt-drivers -a linux.img
<operatingsystems>
<operatingsystem>
<root>/dev/sda2</root>
<boot_drivers>
[list of drivers from the initramfs in a format TBD]
</boot_drivers>
<drivers>
[list of kernel modules]
</drivers>
<boot_loader>
[extra stuff about the bootloader configuration,
list of kernels, default kernel, grub1 or grub2,
config file, ...]
</boot_loader>
I propose a completely new tool added to guestfs-tools to do this,
which will basically pull the current kernel module and grub analysis
code from virt-v2v into a new library in libguestfs-common.
For Windows we actually don't do this in virt-v2v at the moment, so
that would need to be completely new code, likely parsing the
DriverDatabase from the Windows registry.
- - -
For (b), you could specify the location of the Window disk image and
the virtio-win path/ISO to have it attempt to install the drivers in
the disk image:
$ virt-customize -a windows.img \
--inject-virtio-win /usr/share/virtio-win/virtio-win-1.2.3.iso
This would largely involve taking the current virtio-win code from
virt-v2v, turning it into a library, and then adding a new module into
libguestfs-common/mlcustomize. (It would be a good time to refactor
this code.)
- - -
Good? Bad? Let me know what you think ...
I think one large danger is that injecting virtio-win drivers into
existing Windows images is a very invasive operation with a large
potential to go wrong. It would be better to work with the tools that
create these images so that they're able to inject virtio-win drivers
at initial creation. (Or "Inbox" the drivers with Microsoft, but
there may be issues there).
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
nbdkit - Flexible, fast NBD server with plugins
https://gitlab.com/nbdkit/nbdkit
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