Re: [libvirt] [PATCH] Don't validate disk type in virsh attach-disk
Cole Robinson wrote:
Jim Meyering wrote:
> Cole Robinson wrote:
>> virsh attempts to validate the requested disk type, rather than just let
>> the underlying driver do it. This was erroneously denying floppy device
>> attaches. Patch attached.
>
> Hi Cole,
> Your patch would do the job.
> Before:
>
> $ virsh -c test:///default attach-disk 1 s t --type floppy --mode readonly
> error: No support floppy in command 'attach-disk'
>
> with the patch:
>
> $ virsh -c test:///default attach-disk 1 s t --type floppy --mode readonly
> error: this function is not supported by the hypervisor: virDomainAttachDevice
>
> But consider what happens with e.g., "--type bogus".
> Before, it'd mention the invalid type, "bogus".
> With the patch, it doesn't (at least not using the test driver).
> So maybe it'd be better to keep the up-front type check.
>
The idea here is that virsh isn't the one to decide. It could very well
be that driver foo doesn't support cdrom devices, so even though virsh
lets it through, it's still not valid. Only AttachDevice can give us the
full picture.
Sure, I understand that, but if the result of dropping the
harmless (once fixed) up-front check is a diagnostic
that is less helpful, why drop it?
Especially with a 6 or 7-parameter command, it's important
to point out which part is causing trouble, whenever possible.
The alternative is to give better diagnostics from each and every driver.
Sounds like we should just implement AttachDevice for the test
driver:
it could parse the device xml and unconditionally insert it into the
Changing how the test driver handles this case
won't give a better diagnostic for all the other drivers.
guest config. This would certainly be useful in testing the above
virsh
commands (and for testing device attaches in virt-manager, among others