Re: FP in kernelspace

From: Avi Kivity
Date: Sun Jul 30 2006 - 14:09:01 EST

Andi Kleen wrote:

Avi Kivity <avi@xxxxxxxxxx> writes:
> It's also broken for x86-64, which uses sse for floating point, not
> the x87 fpu.

Sorry, that doesn't make sense.

> > kernel_fpu_begin();
> > c = d * 3.14;
> > kernel_fpu_end();

Cannot work on x86-64, even disregarding fp exceptions, because kernel_fpu_begin() doesn't save the sse state which is used by fp math.


Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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