Re: [Qemu-devel] Re: Missing singlestep for already-translated code?

[Aurelien Jarno <aurelien@aurel32.net>]

Jun Koi a écrit :
> On Wed, Apr 14, 2010 at 12:28 AM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> Alexander Graf wrote:
>>> On 13.04.2010, at 15:36, Jan Kiszka wrote:
>>>
>>>> Jun Koi wrote:
>>>>> Hi,
>>>>>
>>>>> I am looking into the singlestep command in monitor interface, and it
>>>>> seems that we only take into account the singlestep flag when we are
>>>>> translating code.
>>>>> So for the already-translated code, we will miss singlestep?
>>>> This feature is broken. For TCG, it should at least flush the
>>>> translation buffer, and for KVM it has to enable single-stepping in the
>>>> kernel. That's what happens automatically when you call cpu_single_step.
>>>> I guess 'singlestep' wants to be somehow orthogonal to this. But this is
>>>> the wrong approach.
>>>>
>>>> Does anyone actually used this feature or still does so? It looks fairly
>>>> redundant to me, kind of a poor-man's gdb front-end as part of the
>>>> monitor console.
>>> Not sure what it does, but I use -singlestep quite a lot to get register dumps for instructions when using -d cpu.
>> Ah, "singlestep" is not about stopping the VM after each instruction but
>> about limiting the TB length to a single instruction. Badly named and
>> poorly documented.
>>
>> In that case, the dynamic switch should already be fine by adding a
>> tb_flush() on enable. Still, someone should also patch at least the docs.
>>

What's the real point of flushing the tb to get it retranslated again?
It will be retranslated in the exact same way.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net