[PATCH] PPC/PPC64: Introduce CPU_HAS_FEATURE() macro

Anton Blanchard anton at samba.org
Sat Feb 5 12:34:26 EST 2005


> This is the patch to evaluate CPU_HAS_FEATURE() at compile time whenever
> possible. Testing showed that vmlinux shrinks around 4000 bytes with
> g5_defconfig. I also checked that pSeries code is completely unaltered
> semantically when support for all CPU types is enabled, although a few
> instructions are emitted in a different order by gcc.
> I have made cpu_has_feature() an inline function that expects the full
> name of a feature bit while the CPU_HAS_FEATURE() macro still behaves
> the same way as in Olofs original patch for now.

Interesting :) However we already get bug reports with the current
CONFIG_POWER4_ONLY option. I worry about adding more options that users
could get wrong unless there is a noticeable improvement in performance.


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