Re: [PATCH] [RFC] Fix for kvm qemu to return control to gdb stub on breakpoints

[Jerone Young <jyoung5@us.ibm.com>]

This is mainly to try and fix the current debug state with using
hardware breakpoints (until your software breakpoint work is ready for
primetime). I actually do need to submit another patch outside of this
for initialization of some variables (which I see is in your patch too),
as it ends up passing down garbage.

For now this is a patch mainly just to get qemu to break into the gdb
stub when a debug interrupt comes in. Though I have a feeling more may
be needed.

On Thu, 2008-05-22 at 18:43 +0200, Jan Kiszka wrote:
> Jerone Young wrote:
> > 1 file changed, 2 insertions(+)
> > qemu/qemu-kvm.c |    2 ++
> > 
> > 
> > Currently breakpoints do not fully work for x86 or any other arch with kvm enable qemu. Control is not being returned by to the gdb stub. This patch add back this ability to return control to the gdb stub when a debug interrupt is hit.
> > 
> > This is in the io thread so it's best to get comments on this. Is it in the best place? Should more be done here?
> > 
> > Signed-off-by: Jerone Young <jyoung5@us.ibm.com>
> > 
> > diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
> > --- a/qemu/qemu-kvm.c
> > +++ b/qemu/qemu-kvm.c
> > @@ -352,6 +352,8 @@ static int kvm_main_loop_cpu(CPUState *e
> >  	    update_regs_for_init(env);
> >  	if (!(env->hflags & HF_HALTED_MASK) && !info->init)
> >  	    kvm_cpu_exec(env);
> > +	if (env->exception_index == EXCP_DEBUG)
> > +	    vm_stop(EXCP_DEBUG);
> 
> This isn't enough, please see
> 
> 	http://permalink.gmane.org/gmane.comp.emulators.kvm.devel/17660
> 
> and the rest of that series - just RFC, but already usable.
> 
> Jan
>