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Re: Implicit altivec vs. linux kernel build
On Sun, 2005-02-27 at 18:56 -0500, David Edelsohn wrote:
> >>>>> Benjamin Herrenschmidt writes:
>
> Ben> Ok. What I need is -mcpu=power4 -maltivec
>
> Sorry, no. -maltivec means generate Altivec code, not just enable
> Altivec instructions and registers. The above option is not different
> than -mcpu=970. There is no DWIM option.
No, that's fine. What I need is
- the entire kernel beeing built with -mcpu=power4
- the raid6 code only beeing built with the additional -maltivec
That should work fine.
The only problem I see is that the day we have a CPU, let's call it
POWER8 for the sake of this demonstration, that has altivec and is
different enough to justify a specific "optimize" option, we'll have to
use -mcpu=POWER8 -mno-altivec for the whole kernel, which makes it
difficult to enable altivec only for the raid6 file since the kenrel
makefiles, afaik, can only add an option to a specific file. Unless
-mcpu=POWER8 -mno-altivec -maltivec is legal ...
Ben.