Re: [Qemu-devel] [RFC PATCH 00/21] Trace updates and plugin RFC

[Pavel Dovgalyuk]

> From: Alex Bennée [mailto:address@hidden
> Pavel Dovgalyuk <address@hidden> writes:
> > One more question about your trace points.
> > In case of using trace point on every instruction execution, we may need
> > accessing vCPU registers (including the flags). Are they valid in such
> > cases?
> 
> They are probably valid but the tricky bit will be doing it in a way
> that doesn't expose the internals of the TCG. Maybe we could exploit the
> GDB interface for this or come up with a named referencex API.
> 
> > I'm asking, because at least i386 translation optimizes writebacks.
> 
> How so? I have to admit the i386 translation code is the most opaque to
> me but I wouldn't have thought changing the semantics of the guests
> load/store operations would be a sensible idea.

Writeback to the registers (say EFLAGS), not to the memory.

Pavel Dovgalyuk