Re: [libvirt] [PATCH 1/3] conf: Add rom.enabled attribute for PCI devices

On Mon, 2018-04-23 at 08:53 +0200, Peter Krempa wrote: > > + The optional <code>enabled</code> attribute can be set to > > + <code>no</code> to disable PCI ROM loading completely for the device. > > + <span class="since">Since 4.3.0 (QEMU and KVM only)</span>. > > Maybe you should mention that any other configration may not be > supported in that case. Good idea. > > @@ -6798,6 +6813,14 @@ virDomainDeviceInfoParseXML(virDomainXMLOptionPtr xmlopt ATTRIBUTE_UNUSED, > > goto cleanup; > > } > > info->romfile = virXMLPropString(rom, "file"); > > + > > + if (info->romenabled == VIR_TRISTATE_BOOL_NO && > > + (info->rombar != VIR_TRISTATE_SWITCH_ABSENT || info->romfile)) { > > I'd explicitly allow empty string in info->romfile, but that would mean > that this needs to be moved to the qemu post-parse callback, since that > is a qemu quirk. > > Justification is that, mgmt tools will be able to use enabled='no' > together with the empty file string without having to do any probing > whether that is a valid configuration. But enabled='no' would be rejected by earlier libvirt releases, which makes the point about avoiding feature detection moot, no?

I would expect management applications that already use (invalid, according to the schema, but working fine by all other counts) file='' to keep using that until they bump their required libvirt version to 4.3.0, and management applications that didn't already use the existing kludge to just go straight for enabled='no'.