Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation

From: Peter Maydell <peter.maydell@linaro.org>
To: "Emilio G. Cota" <cota@braap.org>
Cc: "Daniel P. Berrange" <berrange@redhat.com>,
	Stefan Hajnoczi <stefanha@gmail.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH 00/13] instrument: Add basic event instrumentation
Date: Tue, 29 Aug 2017 10:19:11 +0100	[thread overview]
Message-ID: <CAFEAcA9UzR_HSHxP+mXPPH-ghzruaWW4SzWmDpni0RrdNGc4xw@mail.gmail.com> (raw)
In-Reply-To: <20170826000232.GB29654@flamenco>

On 26 August 2017 at 01:02, Emilio G. Cota <cota@braap.org> wrote:
> An additional "nice to have" would be:
>
> * Allow inlining of TCG code by the instrumenter. Example use case:
>   the instrumenter wants to increment a counter every time a
>   basic block is executed. Instead of calling a callback function on every block's
>   execution, we could just have a translation-time callback to emit at the beginning
>   of the translated block the counter increment. This would be much faster, and
>   is something that all other tools (e.g. DynamoRIO/Pin) implement.

This is a feature I would strongly prefer us not to implement.
It exposes too much of QEMU's internals (ie TCG) to the
instrumentation, and it would be pretty complicated to use.

thanks
-- PMM