Manfred Spraul wrote:
>
> copy_*_user is probably not worth the effort for a Pentium III, but even
> for that function I don't see a problem with SSE, as long as
>
> * the clobbered registers are stored on the stack (and not in
> thread.i387.fxsave)
> * the SSE/SSE2 instructions can't cause SIMD exceptions.
> * noone saves the fpu state into thread.i387.fxsave from interrupts /
> softirq's. Currently it's impossible, but I haven't checked Montavista's
> preemptive kernel scheduler.
>
I overlooked one restriction:
* you must not schedule() with the "wrong" sse registers: switch_to()
saves into i387.fxsave.
This means that copy_*_user isn't that simple.
-- Manfred - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:15 EST