[PATCH] Set cpu explicitly in kernel compiles
kumar.gala at freescale.com
Fri May 6 01:12:42 EST 2005
On May 5, 2005, at 9:23 AM, Tom Rini wrote:
> On Thu, May 05, 2005 at 09:00:50AM -0500, Kumar Gala wrote:
> > On May 5, 2005, at 7:24 AM, Dan Malek wrote:
> > >
> > >
> > >On May 5, 2005, at 1:22 AM, Paul Mackerras wrote:
> > > > If you think we should have -mcpu=xxx on the command line for
> > > > 44x, 8xx, etc., then that's fine, but that is a separate problem
> > >from
> > > > what my patch was addressing (one which my patch might make it
> > >easier
> > > > to fix, though).
> > >
> > >I think that is exactly what we want, although I don't know how
> that is
> > > separate from the patch you sent.? My original comment was the
> > > fixes the problem for only one of the cpu cores, not all of them.?
> > >Which
> > > then led into the subsequent suggestion of making the biarch work
> > > like the past compilers, and we must specific the flags for POWER4
> > > instead of the other way around.? Without explicit -mcpu flags,
> > > existing compiler behavior is just fine .....? but, I guess I'd be
> > >standing
> > > in the way of progress to want this :-)
> > I agree with Dan here. I think we should go ahead and extend the
> > to set -mcpu and -mtune flags for the list of processors we have in
> > "Processor Type". If I'm building a kernel for e500 or 4xx I might
> > well get a kernel that is tuned a bit more for the subarch.
> This is fine.
> > Additionally, there should be some expert override ability, so if I
> > really want to do -mcpu=7455 -mtune=7455 I can.
> Gack, no! It's quite a pain to go from CONFIG_FOO="string" into
> Makefile bits that the one we did have back in 2.4 is gone. That also
> implies gcc finally knows something about these cores that might be
> useful, which I don't think is the case, nor is it likely to be. But
> we did want it, we'd probably go the route x86 has.
I'm not saying it has to be done via a CONFIG option, all I'm saying is
if I want to explicitly use GCC then I would hope we could somehow
disable it being override.
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