Re: [Qemu-devel] [PATCH 0/6] Device state visualization reloaded

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Sep 06, 2011 at 11:28:09AM -0500, Anthony Liguori wrote:
> On 09/06/2011 11:09 AM, Michael S. Tsirkin wrote:
> >On Tue, Sep 06, 2011 at 10:51:26AM -0500, Anthony Liguori wrote:
> >>On 09/06/2011 10:45 AM, Jan Kiszka wrote:
> >>>On 2011-09-06 16:48, Michael S. Tsirkin wrote:
> >>>>I'm afraid that won't be enough to stop people
> >>>>scripting this command - libvirt accessed
> >>>>HMP for years.
> >>>>
> >>>>On the other hand, no QMP command means e.g.
> >>>>libvirt users don't get any benefit from this.
> >>>>
> >>>>What I think will solve these problems, for both HMP and QMP,
> >>>>is an explicit 'debug_unstable' or 'debug_unsupported' command that will
> >>>>expose all kind of debugging functionality making it
> >>>>very explicit that it's an unsupported debugging utility.
> >>>>
> >>>>Proposed syntax:
> >>>>
> >>>>debug_unstable<subcommand>   <options>
> >>>>
> >>>>Example:
> >>>>
> >>>>debug_unstable device_show -all
> >>>
> >>>For HMP, this would needlessly complicate the user interface, nothing I
> >>>would support. People scripting things on top of HMP are generally doing
> >>>this on their own risk and cannot expect output stability.
> >>>
> >>>device_show is like info qtree: the output will naturally change as the
> >>>emulated hardware evolves, information is added/removed, or we simply
> >>>improve the layout. Recent changes on info network are an example for
> >>>the latter.
> >>
> >>Yeah, I'm not worried about stability.  HMP commands that aren't
> >>exposed as QMP commands are inherently unstable and should not be
> >>scripted to.
> >
> >They are also not accessible when using libvirt, right?
> 
> $ virsh human-monitor-passthrough GuestName device_show foo
> 
> Should work.

So how, in the end, will user know it's unsupported?
I don't agree with 'all HMP is unstable' as people
will use it and will come to depend on it.

What I'm asking is something like 'enable_unsupported_commands',
which will expose all kind of stuff.
Could also be extra stuff in existing commands too -
e.g. info pci is a natural way to see config space
for devices.

-- 
MST