Re: [Qemu-devel] Pending MIPS patches

[Fabrice Bellard <fabrice@bellard.org>]

Raphaël Rigo wrote:
> Dirk Behme wrote:
> 
>> Hi Raphaël,
>>
>> maybe you find some time and like to answer to Fabrice's remark 
>> regarding patch 8
>> below?
>>
>> http://lists.gnu.org/archive/html/qemu-devel/2006-06/msg00419.html
>>
>> Would be nice to get as many of the pending MIPS patches applied as 
>> possible.
>>
>> Many thanks
>>
>> Dirk
>>
>> Fabrice Bellard wrote:
>>
>>>> Pending MIPS patches (bugs & improvements):
>>>> ===========================================
>>
>>
>>>> 8. [PATCH] Add mips-user signal handling
>>>> http://lists.gnu.org/archive/html/qemu-devel/2006-06/msg00319.html
>>>
>>>
>>>
>>> OK. Need to check the handling of "env->PC += 4" in 
>>> linux-user/main.c. I want to be sure there is not a better solution. 
>>> Adding setup_rt_frame would be good too.
> 
> Hello,
> there are 2 possibilities to handle this env->PC += 4:
>    -    do a special case wrapper here to avoid increasing PC when it's 
> a sigreturn.
>    -    in do_sigreturn set PC with a -4 offset.
> I chose the first way because I thought it would be cleaner, if anyone 
> was to change this part of the code, then it would be clear that 
> sigreturn directly sets PC. Using the 2nd possibility, one could change 
> this += 4 without knowing do_sigreturn would be affected.
> 
> I also checked if we could get rid of this weird piece of code, but 
> could not find a clear way to do so.
> 
> So i preferred maintainability over efficiency, but if you think
> setting PC with an offset of -4 in signal.c is better, tell me and i 
> will update the patch.

There is another simpler solution and I applied it. BTW, the Linux 
kernel uses the same solution :-)

Fabrice.