Re: System call support in reversible debugging

[Hui Zhu <teawater@gmail.com>]

Cool! I think your explain is very clear. Thanks.  :)

Hui

On Sun, Nov 29, 2009 at 01:40, Michael Snyder <msnyder@vmware.com> wrote:
> Sean Chen wrote:
>>
>> On Sat, Nov 28, 2009 at 2:07 AM, Michael Snyder <msnyder@vmware.com>
>> wrote:
>>>
>>> These are two separate questions.  I think the one you started with
>>> is can gdb record a system call, and the answer is "yes".
>>>
>>>
>>> The issue with mmap has a lot of history, and rather than try to
>>> explain it, I urge you to look up the threads which have "mmap"
>>> or "sbrk" in the title) and read them.
>>>
>>>
>>
>> Thanks for the explanation. That is very kind of you.
>>
>> I am confused about the first question. How does gdb record the system
>> call instructions? You know, they are in the kernel space? It seems
>> that I must have made a mistake somewhere. Please help to clarify.
>>
>> Thanks in advance.
>
> Sean,
>
> I wish I understood this better -- maybe Hui will explain it more.
>
> As I understand it, each system call is recorded as if it were a
> single instruction.  Instead of 'tracing' into the system code,
> we know the specific side effects for each system call, and for
> instance if the syscall will write to a buffer we take a snapshot
> of that buffer first.
>
> Michael
>
>