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SubjectRe: [1/4] better i386 CPU selection
On Fri, Jan 16, 2004 at 04:01:33PM -0800, Andrew Morton wrote:
> I must say that I'm a bit wobbly about Adrian's recent patches, simply
> because of the overall intrusiveness and conceptual changes which they
> introduce.

The only patch where I'd say this really applies to is
better-i386-cpu-selection.patch .

I'm really happy that you added it in the latest -mm and I'm even more
happy that I haven't yet heard of any major breakage it has caused.

But it's your decision whether you like this patch or prefer to drop it.

> Remind me again, what did they buy us?

The main effect is that better-i386-cpu-selection.patch makes it easier
for people who configure kernels that should work on different CPU
types. A user (= person compiling his own kernel) does no longer need
any deeper knowledge when e.g. configuring a kernel that should run on
both an Athlon and a Pentium 4 - he simply selects all CPUs he wants to
support in his kernel.

As a side effect, this patch allows further optimizations based on the
fact that e.g. a kernel for an i386 no longer needs to support an Athlon
which can be used to omit support for non-selected CPUs [1].


[1] e.g. there's no need to include arch/i386/kernel/cpu/amd.c in your
kernel if the kernel should only run on a 386;
I made two such example patches that are _way_ too ugly for merging
but show that this CPU selection scheme makes some more space
savings possible


"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

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