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Date: Fri, 25 Jul 2014 16:05:34 +0800
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Subject: Re: [Qemu-devel] [PATCH] cpu-exec: make TBs generated codes
 unlinked when -singlestep
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To: Peter Maydell <peter.maydell@linaro.org>, Richard Henderson <rth@twiddle.net>
Cc: Riku Voipio <riku.voipio@iki.fi>, QEMU Developers <qemu-devel@nongnu.org>


On 07/25/2014 03:45 PM, Peter Maydell wrote:
> On 25 July 2014 08:41, Richard Henderson <rth@twiddle.net> 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