Re: [PATCH] x86_64 prefetchw() function can take into account CONFIG_MK8 / CONFIG_MPSC

From: Andi Kleen
Date: Thu Jun 23 2005 - 08:15:16 EST

On Thu, Jun 23, 2005 at 02:53:14PM +0200, Eric Dumazet wrote:
> Andi Kleen a ?crit :
> >On Thu, Jun 23, 2005 at 11:32:34AM +0200, Eric Dumazet wrote:
> >
> >>If we build a x86_64 kernel for an AMD64 or for an Intel EMT64, no need
> >>to use alternative_input.
> >>Reserve alternative_input only for a generic kernel.
> >
> >
> >An EM64T kernel should still boot on AMD64 and vice versa. Rejected.
> >
> >-Andi
> >
> >
> OK, I wrongly assumed the 'MK8' or 'MPSC' choices were like x86 choices :
> A kernel compiled for a Pentium-4 will not run on a i486.
> But then what is the meaning of the choice "Generic-x86-64" in the
> "Processor family" menu ?
> The Help message is : CONFIG_GENERIC_CPU: Generic x86-64 CPU.

Optimize for both. It's a catch all setting for future changes
and does not do too much right now.

It also won't pass any -mcpu=... arguments to gcc. This currently
doesn't make any difference (gcc x86-64 default is to optimize
for K8), but I assume it might at some point when gcc gets
a "combined" mode that optimizes for both Intel and AMD CPUs.


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