Re: [patch 04/41] cpu ops: Core piece for generic atomic per cpu operations

Rusty Russell
2008-06-17T00:25:16Z

On Tuesday 17 June 2008 00:52:08 Christoph Lameter wrote:
> On Sun, 15 Jun 2008, Rusty Russell wrote:
> > > 3. Some hooks for arches to override particular behavior as needed.
> > > F.e. IA64 allocates percpu structures in a special way. x86_64
> > > needs to do some tricks for the pda etc etc.
> >
> > IA64 is going to need some work, since dynamic percpu addresses won't be
> > able to use their pinned TLB trick to get the local version.
>
> The ia64 hook could simply return the address of percpu area that
> was reserved when the per node memory layout was generated (which happens
> very early during node bootstrap).

Apologies, this time I read the code. I thought IA64 used the pinned TLB area
to access per-cpu vars under some circumstances, but they only do that via an
arch-specific macro.

So creating new congruent mappings to expand the percpu area(s) is our main
concern now?

Rusty.