[libvirt] [PATCH 0/2] Disable floppy disk for PowerPC VMs

madhu pavan kmp at linux.vnet.ibm.com
Thu Jul 30 11:41:42 UTC 2015

On 07/29/2015 06:25 PM, Andrea Bolognani wrote:
> On Fri, 2015-07-24 at 15:29 -0400, Kothapally Madhu Pavan wrote:
>> This is an attempt to fix:
>> Libvirt BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1180486
>> Libvirt currently assumes ISA_based floppy disks to be available
>> across all
>> architectures and machine types. However, PowerPC Book 3S compatible
>> ('ie pseries)
>> virtual machines do not support Floppy disks.
>> This patch series prevents libvirt from launching ppc64[le] -based
>> 'pseries'
>> VMs with floppy devices.
> Hi,
> sorry for not replying right away.
> I started looking into that bug a while ago but I got sidetracked
> shortly afterwards, so I don't have much to show for it. I'd like
> to share my opinion on the matter anyway.
> I believe you're basically following the right approach, eg. avoid
> setting floppy-related capabilities and erroring out afterwards if
> attempts are made to use devices that require such capabilites.
> However, I think the implementation should be a little more
> generic: ideally, the code would contain no references to the
> ppc64 architecture and whether or not floppy disks are be allowed
> would be determined by probing the QEMU binary.
> Writing the code this way would allow us to handle automatically
> other architectures where floppy disks do not make sense[1] and
> situations where floppy support is not available[2].
> If that turns out not to be possible or practical, at the very
> least the check should be performed in one single spot, and not
> replicated a dozen times thorough the library.So,
As, present method of capabilities parsing uses "qemu -h", and the list 
received in this case is arch agnostic. So, we cannot do arch-specific 
caps parsing unless qemu undergoes a rewrite. I will be providing a new 
patch set with as minimal changes as possible.

Madhu Pavan.

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