Re: [libvirt] [Qemu-devel] [PATCH v2] hmp: allow cpu index for "info lapic"
On Wed, Jul 19, 2017 at 10:02:04AM -0500, Eric Blake wrote:
[adding libvirt]
On 07/19/2017 07:41 AM, Eduardo Habkost wrote:
>> virsh qemu-monitor-command --domain rhel6.8 --hmp --cmd "cpu 1"
>> virsh qemu-monitor-command --domain rhel6.8 --hmp --cmd "info lapic"
>> dumping local APIC state for CPU 0
>
> Right, the "cpu" command is useless inside a
> 'human-monitor-command' QMP command. The 'cpu-index' argument
> should be used instead. should make "cpu" print an error if ran
> inside 'human-monitor-command' instead of silently pretend it
> worked.
>
> If virsh doesn't support the 'cpu-index' argument to
> 'human-monitor-command',
It doesn't. Perhaps we should add that as a future libvirt-qemu.so API
addition, although it's probably easier to just use QMP than HMP when
using 'virsh qemu-monitor-command' if HMP doesn't do what you want.
Or special case the "cpu 1" command - ie notice that it is being
requested and don't execute 'human-montor-command'. Instead just
record the CPU index, and use that for future "human-monitor-command"
invokations, so we get full compat with the (dubious) stateful HMP
semantics that traditionally existed.
> it's possible to work around that
> limitation by building your own QMP command. e.g.:
>
> # virsh qemu-monitor-command f26test
'{"execute":"human-monitor-command",
"arguments":{"command-line":"info lapic",
"cpu-index":1}}' | jq -r '.return'
Indeed, there's the use of QMP to work around the HMP deficiency.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
Regards,
Daniel
--
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