[M3devel] a note on user thread -- *context not 'universal'

[Tony Hosking]

makecontext/getcontext/setcontext and friends are both available on  
Darwin and should do FP state properly.

On 13 Jan 2009, at 01:30, Olaf Wagner wrote:

> Quoting Jay <jay.krell at cornell.edu>:
>
>> Do we really need the assembly _fpsetjmp?
>
> IIRC, I introduced fpsetjmp/fplongjmp when I made the first FreeBSD  
> code,
> as FreeBSD does not care about storing the floating point state,
> and spurious FP errors occured when switching threads by longjmp.
> I think Bruce Evans contributed the FreeBSD assembler code.
>
> It may be that Darwin, which is derived from FreeBSD in certain areas,
> has inherited this problem (I don't remember offhand, and I haven't
> done much BSD or M3 programming in recent months). I think no other
> systems needed to use specially crafted setjmp/longjmp pairs to
> accomodate the M3 user threads.
>
> Olaf
> -- 
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