FP context switching on i386

[Till Straumann]

Thomas Doerfler wrote:
> Till,
>
> although I am not at all familiar with i386 ABI stuff, I would guess
> that we have to save the context during a task switch, at least when it
> was forced due to a interrupt (e.g. timer) event. In these cases there
> is no function call involved for the function that uses the FP context.
>   
I think you're right, Thanks.

T.
> wkr,
> Thomas.
>
>
> Till Straumann schrieb:
>   
>> I thought the i386 sysv ABI said that FP registers
>> are not preserved across function calls -- doesn't
>> this mean that there is no need for saving/restoring
>> the FP context ? Am I missing something ?
>>
>> I was thinking about what it takes to support SSE
>> and I believe it may essentially come for free
>> since XMM registers seem not to be callee saved
>> either. Hard to find that information though since
>> e.g.,
>>
>> http://www.sco.com/developers/devspecs/abi386-4.pdf
>>
>> doesn't mention SSE yet.
>>
>> -- Till
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>
>
>