Re: [Qemu-devel] [PATCH v3 5/7] hmp: Add info commands for preconfig

[Eduardo Habkost <ehabkost@redhat.com>]

On Tue, Jun 12, 2018 at 09:00:20AM +0200, Markus Armbruster wrote:
> Igor Mammedov <imammedo@redhat.com> writes:
> 
> > On Mon, 11 Jun 2018 15:40:16 -0300
> > Eduardo Habkost <ehabkost@redhat.com> wrote:
> >
> >> On Mon, Jun 11, 2018 at 02:01:52PM +0200, Markus Armbruster wrote:
> >> > * Eduardo, why does "info numa" have no QMP equivalent?
> >> 
> >> Nobody ever asked for one, which seems to qualify as "only for
> >> human users".
> >> 
> >> Should we add an equivalent QMP command even if we don't expect
> >> anybody to use it?
> 
> The hard requirement for QMP from day one was "provide everything
> machine clients need".  To avoid speculation and endless arguments about
> what might be needed / not needed, we resolved to approximate this by
> "provide everything, except stuff that's *clearly* of no use to
> machines".
> 
> When you think a command is such an exception, you should explain why in
> its commit message.

It's not an exception nor it needs to be one.  I was just not
aware of the above approximation.


> 
> Note that HMP need not provide the functionality in the exact same
> packaging.  For instance, it's fine to have building blocks in QMP, and
> just a high-level command in HMP.  However, the latter must be
> implemented with the building blocks to make it obvious that QMP
> provides the same functionality.
> 
> For additional references, see
> Message-ID: <87d0x1p6go.fsf@dusky.pond.sub.org>
> https://lists.nongnu.org/archive/html/qemu-devel/2018-06/msg02176.html
> 
> > we inderectly can fetch numa info via QMP, using 
> >   query-hotpluggable-cpus
> > for CPU mapping and
> >   query-memory-devices
> > for (NV|PC)-dimm devices, however there is no QMP way for getting
> > for numa mapping of initial RAM nor configured numa nodes
> > (not counting querying CLI options).
> 
> Sounds like most of the building blocks are already there.  The
> "obviousness" isn't.
> 
> > So perhaps we need info 'numa' equivalent for QMP which would give
> > the same amount of information as HMP in one query.
> 
> I'd appreciate patches to get us to "QMP has the building blocks, and
> HMP is implemented with them".

Agreed.

-- 
Eduardo