Re: [patch 05/14] percpu: Use a Kconfig variable to configure arch specific percpu setup

Rusty Russell
2007-11-28T02:29:54Z

On Wednesday 28 November 2007 05:14:47 Christoph Lameter wrote:
> On Tue, 27 Nov 2007, Rusty Russell wrote:
> > Have you considered moving x86-64's setup_per_cpu_areas into generic
> > code? It's a bit messier because some archs might not have set up NUMA
> > stuff yet, but it's logically generic...
>
> Yes that will happen later. This is just the early cleanup work. I
> plan to generally bring the two x86 arches in line. The pda will be
> folded into the per cpu area and after that its easy to do.

Unfortunately, we tried to get rid of the x86-64 pda (like i386) but you lose
the ability to use the stack protection config option. That's because it
assumes that gs:0x68 (or something) is the stack canary; we need a YA gcc
change to make this gs:__builtin_stack_canary_off (where gcc can emit
__builtin_stack_canary_off as a weak absolute symbol, so we can override it
for the kernel.

Cheers,
Rusty.