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

"Daniel P. Berrange" <berrange(a)redhat.com&gt; writes: > On Thu, May 02, 2013 at 10:40:06AM -0500, Anthony Liguori wrote: >> Kevin Wolf <kwolf(a)redhat.com&gt; 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 ? Given a device, how do you figure out if it's a cdrom/floppy/whatever without hard coding a mapping of class name -> device type. Pretty sure libvirt just has a class name mapping, right?