Re: [Qemu-devel] [RFC][PATCH v3 00/24] instrument: Let the user wrap/override specific event tracing routines

[Stefan Hajnoczi <stefanha@gmail.com>]

On Sun, Apr 28, 2013 at 09:25:15PM +0200, Lluís Vilanova wrote:
> Stefan Hajnoczi writes:
> 
> > On Fri, Apr 26, 2013 at 02:15:46PM +0200, Lluís Vilanova wrote:
> > Advanced users will have to modify the QEMU source.
> 
> >> > Basically I think putting a stable API in place here isn't going to fly.
> >> > In terms of the tracing subsystem I don't mind, but I think it's a
> >> > question for the larger QEMU community.
> >> 
> >> What are you referring to as an API? The tracing events and their signatures?
> 
> > The interface that dynamic instrumentation libraries use to interact
> > with QEMU.  That means "stable" tracing events plus any operations that
> > libraries can perform (stop/stop vcpu, peek/poke memory, dirty bitmaps,
> > MMU, interrupts, etc).
> 
> Not all events require being "stable", just a few that I established as
> "abstract" and relate to some very generic guest state (which in their most
> basic form can be boiled down to 5). As for the rest of the API and more
> controversial events, as I said I have no problem in maintaining a separate
> branch.

Can you split the work into two patch series:
1. Target-independent TCG events (e.g. vbbl_begin)
2. "custom" trace backend that links custom C trace event handler
   functions - but without dynamic libraries or stable API.

It loses the dynamic library and stable API features but would be easy
to merge.

Stefan