Messages in this thread |  | | From | (Malcolm Beattie) | Subject | Re: Linux support for Intel MMX CPU's | Date | 20 Aug 1996 09:35:11 GMT |
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In article <Pine.LNX.3.94.960816181143.20286C-100000@vci.vistacom.fi>, =?ISO-8859-1?Q?Johan_Myr=E9en?= <jem@vistacom.fi> wrote: >On Fri, 16 Aug 1996, Michael Mansour wrote: > >> During 1997, MMX will be released by Intel with their CPU's, I am >> wondering whether Linux will be able to take advantage of these advanced >> multimedia capabilities at chip level? Will it be kernel support or app >> support or both? > >The kernel itself does not need multimedia capabilities, but I'm sure some >kernel hacker with a sufficiently twisted mind (especially Linus himself) >can come up with some interesting uses for the new instructions in the >kernel code :-) > >Other than that, MMX is purely a user level thing. Applications can start >using the new instructions and be happy. No kernel support is needed >(except perhaps for /proc/cpuinfo). The MMX registers map to the FPU >registers, so no new registers need to be saved on context switch.
Linus mentioned that task switching used tricks to be lazy about FPU state saving. I can't find the relevant code right now. Maybe somebody should check that these MMX instructions don't bypass whatever method Linux uses to trigger a forced save of FPU state.
--Malcolm
-- Malcolm Beattie <mbeattie@sable.ox.ac.uk> Oxford University Computing Services "Widget. It's got a widget. A lovely widget. A widget it has got." --Jack Dee
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