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SubjectRe: ABI change for device drivers using future AVX instruction set
> 3. When compiling a device driver, the compiler may insert implicit 
> calls to library functions such as memcpy and memset. These functions
> typically have a CPU dispatcher that chooses the largest register size
> available. The device driver may therefore use YMM registers without the
> knowledge of the programmer and without compiling with the AVX switch on.

Linux uses its own routines in these cases - and in fact for MMX we
generally avoid kernel usage in order to avoid the overheads (ditto FP).

> A decision on this question should be made and published in the ABI so
> that people can make compatible device drivers.

The beauty of the Linux kernel being source based - we don't have to worry
about ABI problems like this.

Alan



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