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Re: MKSOFTFLOAT for evbppc
On Wed, 26 Sep 2012, David Brownlee wrote:
> Thats disappointing, but understandable :)
> Is there some variant that will get gcc to use the fp registers but
> not the instructions (assuming it doesn't trap on fp register
> usage..): -mno-fused-madd -mno-mulhw -msimple-fpu looks to turn off
> some instructions but not all.
Well, if you have no FPU you have no FPU registers. If you have no FPU
registers, any instructions to access them will fault. If you're going to
fault anyway, you may as well do the whole FP operation in the kernel
thaty way you only take one fault for the FPOP instead of one fault to
read the register contents and another fault to write the results back.
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