Re: [Qemu-devel] [PATCH] cpu-exec: make TBs generated codes unlinked when -singlestep

[Jincheng Miao]

On 07/25/2014 03:45 PM, Peter Maydell wrote:
> On 25 July 2014 08:41, Richard Henderson <address@hidden> wrote:
> > On 07/24/2014 09:37 PM, Peter Maydell wrote:
> > > Huh? We already don't emit goto_tb if single-stepping, surely?
> > > (Well, I guess some of the backends might well be broken, but
> > > in that case they probably don't get the other bits of singlestep
> > > support right either...)
> > Indeed.  I noticed this a month or so ago.
> >
> > Almost all backends check the gdb env->single_step to prevent goto_tb, but
> > forget about the tcg debugging singlestep.
> Oh, we have two flavours of singlestep? That's confusing...

IMHO, CPUState->singlestep_enabled is a cpu execute mode, for emulating
it, an exception should be raised.

But '-singlestep' from command line rules qemu how to generate TBs and
their generated codes. In this situation, a TB only contains one 
instruction,
and should be unlinked.

Am I right?

> (I'm currently working on the ARMv8 architectural singlestep,
> which will make 3 for target-arm.)
>
> thanks
> -- PMM