Re: SMTC support status in latest git head.

["Kevin D. Kissell" <kevink@paralogos.com>]

On 01/04/11 09:54, Anoop P A wrote:
> On Tue, 2011-01-04 at 09:21 -0800, Kevin D. Kissell wrote:
>> I'm trying to figure out a reason why your change below should help, and
>> offhand, modulo tool bugs, I don't see it.  I'm assuming that your diff
>> below is a diff relative to the pre-patch stackframe.h.   I wouldn't
> Yes patch created against stock code .
>
>> bless it as an alternative because it moves code and comments
>> unnecessarily - all you should really have to do is to move the
>>
>>
>>    190                 mfc0    v1, CP0_STATUS
>>    191                 LONG_S  $2, PT_R2(sp)
>>
>> to be just after the #endif /* CONFIG_MIPS_MT_SMTC */ at around line 201.
> Actually I just moved code under CONFIG_MIPS_MT_SMTC to previous block
> of code ( which store $0 ) . git diff did the rest on behalf of me :)
>
>> If moving the save of zero to PT_R0(sp) actually makes a difference,
>> it's evidence that you've got problems in your toolchain (or, heaven
>> forbid, your pipeline)!
> In previous version of patch usage of V0 was creating issue. I have
> verified this with previous version of code ( working code before
> David's instruction rearrangement patch.) .

Argh.  It's not very clearly commented, but it looks as if the system 
call trap handler has an implicit assumption that v0 has never been 
changed by SAVE_SOME, TRACE_IRQS_ON_RELOAD, or STI.  So yeah, moving the 
code around to fix the v1 conflict ends up being better than using v0 - 
otherwise, we'd need to add a LONG_L v0, PT_R2(sp) somewhere after the 
LONG_S v0, PT_TCSTATUS(sp) of the original patch.

             Regards,

             Kevin K.