[libvirt] [Qemu-devel] [PATCH 3/3] gtk: add devices menu to allow changing removable block devices

[Daniel P. Berrange]

On Thu, May 02, 2013 at 10:40:06AM -0500, Anthony Liguori wrote:
> Kevin Wolf <kwolf at redhat.com> writes:
> >> >> +
> >> >> +        if (strcmp(type, "ide-cd") == 0) {
> >> >> +            disk_type = DT_CDROM;
> >> >> +        } else if (strcmp(type, "isa-fdc") == 0) {
> >> >> +            disk_type = DT_FLOPPY;
> >> >> +        } else {
> >> >> +            disk_type = DT_NORMAL;
> >> >> +        }
> >> >
> >> > Same thing here, comparing against strings is a hack. Devices should
> >> > probably have a property that says what kind of device they are.
> >> 
> >> Ack, this is nasty.  I would like to eliminate this.  There is a type
> >> field in BlockInfo but:
> >> 
> >> # @type: This field is returned only for compatibility reasons, it should
> >> #        not be used (always returns 'unknown')
> >> 
> >> I vaguely remember this happening but I don't remember the specific
> >> reason why.  I would definitely prefer that we filled out type
> >> correctly.
> >> 
> >> I think Markus was involved in this.  Markus or Luiz, do you remember
> >> the story here?
> >
> > The reason is that BlockInfo is about the backend and it simply doesn't
> > know (ever since we introduced if=none, this was buggy, so we just
> > abandoned it at some point). We would have to ask the device, not the
> > block layer.
> 
> Yes, this makes sense.  We could introduce an interface that all disks
> implemented that returned information about whether it was a CD-ROM,
> Floppy, etc.
> 
> How does libvirt cope with this today?  I presume they do something
> similar to what this patch is doing in terms of hard coding device
> names.

Sorry, not really sure what your question is here - how does libvirt
cope with what exactly ?

Daniel
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