Re: [Xen-devel] [PATCH v5 2/5] libxl: add query function for backend support by device model

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Mar 30, 2016 at 03:26:23PM +0100, Wei Liu wrote:
> On Wed, Mar 30, 2016 at 04:11:39PM +0200, Juergen Gross wrote:
> > On 30/03/16 16:09, Wei Liu wrote:
> > > On Wed, Mar 30, 2016 at 04:02:20PM +0200, Juergen Gross wrote:
> > >> On 30/03/16 15:53, Wei Liu wrote:
> > >>> On Wed, Mar 30, 2016 at 02:05:55PM +0200, Juergen Gross wrote:
> > >>>> Add a function to query whether the device model is supporting a
> > >>>> specific backend type. The device model is writing the supported
> > >>>> backend types to Xenstore on startup. The new query function checks
> > >>>> for the appropriate entry to be present.
> > >>>>
> > >>>> As not all versions of qemu are capable to indicate support of
> > >>>> specific backends the query function is to be called with an indicator
> > >>>> whether the default return value should be "supported" (in case qemu
> > >>>> doesn't know set any support information) or "not supported".
> > >>>>
> > >>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > >>>
> > >>> The code itself looks straightforward enough.
> > >>>
> > >>> But note that this is a new protocol that needs to be supported
> > >>> essentially forever. I've CC QEMU maintainers for their input.
> > >>
> > >> Okay, I'll send the qemu patch now.
> > >>
> > > 
> > > And also a patch to docs/misc/xenstore-paths.markdown please.
> > 
> > Aah, sure.
> > 
> 
> Actually wait, I think all QEMU nodes are either under documented or I
> looked at the wrong place.

I don't think there is anything missing, in term of PV protocol, which go
through xenstore. Is there a node in particular that you are thinking of?

> Anthony, how should we document the protocol between QEMU and toolstack?
> Did I look at the wrong place?

I think xenstore-paths.markdown would be a good place to document this
protocol.

-- 
Anthony PERARD

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