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Re: -mno-sse and -mno-sse2 broken on opteron?
On 2005-01-07, at 00:41, Richard Henderson wrote:
On Thu, Jan 06, 2005 at 08:44:36PM +0100, Marcin Dalecki wrote:
That's a non issue. You simply don't use floating point arithmetics
when for kernels.
How naieve you are. The compiler is getting smart enough to use
SSE for non floating-point applications. While looking at a bug
the other week, I caught it doing exactly that with a bit of
Then you are simply using a "different" definition of "floating point
then factual on the architecture at hand.
If you're not either turning off sse, or saving and restoring all
sse state on entry to the kernel, then you risk data corruption.
And you are 100% sure the cost of this will be higher then constraining
compiler to a defective API? If the compiler is going to use them for
not associated necessarily with floating point calculations you will
find yourself in
a situation where most of the user space will ask you indirectly to
registers on stack anyway... So what? You will soon give the trick of
floating point register file saving on context switch factually up and
penalty of a constrained register file anyway.