[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH, RFC] trace: implement guest tracepoint passthro
From: |
Lluís |
Subject: |
Re: [Qemu-devel] [PATCH, RFC] trace: implement guest tracepoint passthrough |
Date: |
Mon, 29 Aug 2011 14:51:43 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
Stefan Hajnoczi writes:
> The ability to trace from the guest can be handy, so I think we should
> have this feature. Please add documentation on how to hook it up
> (e.g. how people would use this for other firmware/guest code and/or
> other architectures).
> Guest and QEMU need to agree on event IDs. The guest code needs to be
> built with QEMU and they may not function with other QEMU builds or
> guest builds. This is fine for development but not feasible when QEMU
> and the guest code are built or provided separately.
> I suggest we merge this as a development feature that can be used when
> bringing up new architectures, debugging guest code, or for some types
> of performance work. This feature falls under the Do-It-Yourself
> area, where things could break relatively easy but developers who wish
> to use it should be able to get it working in their area.
This sounds is indeed interesting.
I suppose I could even use this as a backdoor mechanism for the guest to
communicate with QEMU. The only problem I see is that fw_cfg is one-way
(i.e., QEMU cannot return any data back to the guest), as opposed to a
backdoor mechanism based on a virtual device or "magic" instructions.
Lluis
--
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
Tollbooth