Messages in this thread |  | | Date | Wed, 20 Sep 2000 12:51:50 -0400 | From | Brian Gerst <> | Subject | Re: Question: Using floating point in the kernel |
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Timur Tabi wrote: > > ** Reply to message from "Lyle Coder" <x_coder@hotmail.com> on Wed, 20 Sep 2000 > 01:50:05 GMT > > > You cannot use MMX registers in the kernel either, since the kernel doesen't > > save and restore FX state (fxsave, fxrstor) either (just like > > (fsave/frstor). > > But what about these source files: > > include/asm-i386/mmx.h (which several other header files, like asm-i386/page.h, > include) > arch/i386/lib/mmx.c > arch/i386/lib/usercopy.c > > It appears that MMX is being used in the kernel already.
Only under carefully controlled conditions. The MMX copy routines are only used when the overhead of saving the user floating point register state can be marginalized by the size of the copy.
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