Re: [RFC 00/15] x86_64: Optimize percpu accesses

From: Ingo Molnar
Date: Wed Jul 09 2008 - 15:28:53 EST



* Mike Travis <travis@xxxxxxx> wrote:

> * x86_64: Rebase per cpu variables to zero
>
> Take advantage of the zero-based per cpu area provided above. Then
> we can directly use the x86_32 percpu operations. x86_32 offsets
> %fs by __per_cpu_start. x86_64 has %gs pointing directly to the
> pda and the per cpu area thereby allowing access to the pda with
> the x86_64 pda operations and access to the per cpu variables
> using x86_32 percpu operations.

hm, have the binutils (or gcc) problems with this been resolved?

If common binutils versions miscompile the kernel with this feature then
i guess we cannot just unconditionally enable it. (My hope is that it's
not necessarily a binutils bug but some broken assumption of the kernel
somewhere.)

Ingo
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