[patch][5/5] powerpc: Add the general support for Embedded Floating-Point instructions

[Kumar Gala]

On Jan 12, 2007, at 5:05 AM, Benjamin Herrenschmidt wrote:

>
>>> Why do we need a separate ret_from_except_spe_full?
>>
>> I'm not sure if the kernel will return from exception in a multi- 
>> thread
>> way, but the truth is if restoring EVRs in exsiting  
>> ret_from_except_full,
>> some non-SPE exception will try to retore EVR. At that time, the
>> MSR[SPE] may not be enabled, which will cause error.
>
> Hrm... you can restore them before returning from the exception if you
> are careful about doing that with preempt/irqs off I suppose.

Which is what I thought having the exception be EXC_XFER_EE and  
flush_spe_to_thread should get you.

I dont see any reason to dirty up the 'exception' path for stuff we  
can do in C code.

- k