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

[Michael S. Tsirkin]

On Fri, Aug 26, 2011 at 04:48:10PM +0200, Jan Kiszka wrote:
> More than one year ago I posted some patches to add a monitor command
> callend device_show. The purpose of that command is to dump the state of
> some qdev device based on its vmstate.
> 
> To improve the usability of that interface, the previous series also
> tried to create a canonical qdev tree path name format and even added
> monitor command expansion. That format created quite a few discussions,
> and we never came to some conclusion.
> 
> As device_show is still a useful tool for debugging but qdev structuring
> and addressing may significantly change in the near future, I decided to
> reanimate those patches while avoiding almost any change of the
> addressing scheme. The only one I propose is automatic ID assignment for
> anonymous devices so that any qdev device is in principle addressable
> (e.g. APIC and IO-APIC on x86).
> 
> As back then, device_show remains HMP-only to avoid any stable ABI
> issues around QMP.

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


-- 
MSt