Messages in this thread | | | Date | Wed, 25 Jun 2008 21:14:43 +0100 | From | Alan Cox <> | Subject | Re: ABI change for device drivers using future AVX instruction set |
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> 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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