Re: [PATCH 6/6] docs: document panic device 'pvpanic-pci'
On Thu, Feb 09, 2023 at 06:32:12PM +0100, Peter Krempa wrote:
On Thu, Feb 09, 2023 at 08:41:01 -0800, Andrea Bolognani wrote:
> On Wed, Feb 08, 2023 at 01:09:05PM +0100, Peter Krempa wrote:
> > On Wed, Feb 08, 2023 at 12:49:05 +0100, Kristina Hanicova wrote:
> > > +++ b/docs/formatdomain.rst
> > > @@ -7940,6 +7940,7 @@ Example: usage of panic configuration
> > > - 'hyperv' - for Hyper-V crash CPU feature. :since:`Since
1.3.0, QEMU and
> > > KVM only`
> > > - 's390' - default for S390 guests. :since:`Since 1.3.5`
> > > + - 'pvpanic' - for PCI pvpanic devicen :since:`Since 9.1.0,
QEMU and KVM only`
> >
> > s/devicen/device/
> >
> > Also is KVM really required? I'd expect that it will also work with TCG
> > VMs.
>
> I think so as well. But to be honest I'm unclear on what "QEMU and
> KVM only", as used extensively throughout the document, is intended
> to mean. Does it mean "only when using the QEMU driver and its KVM
> domain type", or rather "only when using the QEMU or KVM domain
> type"? The latter sounds more likely to me, and it would be accurate
> for the pvpanic-pci device.
Generaly in our docs "QEMU only" means that it works only with the qemu
driver/hypervisor, thus I don't think the interpretation that <domain
type='qemu'> or kvm will work here.
A few counterexamples:
Watchdog devices
A virtual hardware watchdog device can be added to the guest via
the watchdog element. Since 0.7.3, QEMU and KVM only
Memory balloon device
A virtual memory balloon device is added to all Xen and KVM/QEMU
guests. It will be seen as memballoon element. It will be
automatically added when appropriate, so there is no need to
explicitly add this element in the guest XML unless a specific
PCI slot needs to be assigned. Since 0.8.3, Xen, QEMU and KVM
only
Firmware
The firmware attribute allows management applications to
automatically fill <loader/> and <nvram/> elements and possibly
enable some features required by selected firmware. [...] Since
5.2.0 (QEMU and KVM only)
ROM
The optional file attribute contains an absolute path to a binary
file to be presented to the guest as the device's ROM BIOS. This
can be useful, for example, to provide a PXE boot ROM for a
virtual function of an sr-iov capable ethernet device (which has
no boot ROMs for the VFs). Since 0.9.10 (QEMU and KVM only)
All of the above work perfectly fine with TCG, at least as far as I
know.
There are a few instances of "(QEMU/KVM only)" in the document, and
even a couple of "(KVM only)".
tl;dr
We're awfully inconsistent about this. I'm okay with dropping the
"and KVM" part from this patch. I'd also be very much okay with
someone[1] going through the document and changing it to use a
single, unambiguous way to indicate whether a feature works with TCG
or is restricted with KVM.
[1] No, I'm not volunteering to be that someone :)
--
Andrea Bolognani / Red Hat / Virtualization