[PATCH] Set cpu explicitly in kernel compiles

[Paul Mackerras]

Dan Malek writes:

> The only reason I mentioned it is the "new" default behavior of the
> compiler is appropriate for only a very small subset of the cores,

Subset of which set of cores?  Do you mean "small subset of 6xx cores"
or "small subset of PPC cores"?  I didn't change anything for non-6xx
cores except to take out -mstring (if you really want that back, say
so :).  If you mean "small subset of 6xx cores" then are you objecting
to the specific choice of "-mcpu=603 -mtune=7450", or what?

> My concern wasn't specifically for which options I wanted, but
> rather for the mechanism to set all of them now that it appears
> we need to do that.

We don't *need* to do it any more than we did before.  It's easy to
set options for 4xx, 8xx, etc. - just say the word.

> OK, but we still need some kind of indication from the configuration
> process.  It seems to me it would be easier (and more logical) to
> have the default behavior work like it has in the past, and use the
> special options for the POWER4, which we already know in
> the configuration.

The problem isn't for POWER4, the problem is biarch gcc4 optimizing
for POWER4 when we are compiling for 6xx.

Paul.