Re: Inclusion of x86_64 memorize ioapic at bootup patch

Andi Kleen
2006-01-06T18:59:16Z

On Fri, Jan 06, 2006 at 01:02:16AM -0700, Eric W. Biederman wrote:
> Andrew Morton <akpm@osdl.org> writes:
> >
> > Please don't top-post.
> >
> >>
> >> On 1/2/06, Vivek Goyal <vgoyal@in.ibm.com> wrote:
> >> > Hi Andi,
> >> >
> >> > Can you please include the following patch. This patch has already been
> > pushed
> >> > by Andrew.
> >> >
> >> >
> > http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.15-rc5/2.6.15-rc5-mm3/broken-out/x86_64-io_apicc-memorize-at-bootup-where-the-i8259-is.patch
> >
> > IIRC, I dropped this patch because of discouraging noises from Andi and
> > because underlying x86_64 changes broke it in ugly ways.
>
> Ok. I just as extensively as I could and I can't find the under laying
> x86_64 changes that Andi mentioned he was working on. I have looked
> in current -mm and in Andi merge and experimental quilt trees. It
> could be that I'm blind but I looked and I did not see them.
>
> Even in the discussion where this was mentioned there never was a
> semantic conflict. But rather two patches passing so close they
> touched the same or neighboring lines of code.
>
> > It needs to be
> > redone and Andi's objections (whatever they were) need to be addressed or
> > argued about.
>
> The difference was one of approach. Andi wanted us to treat the apics
> as black boxes and save and restore register values with no regard as
> to what the registers did. This is theoretically more future proof,
> but it looses flexibility.

Well I still think it would be better to do it in the generic way,
but i'm not feeling very strongly about it anymore.

> to change the destination cpu, in the kexec on panic case. This
> is something that cannot be done if we simply saved off the registers.
>
> > Right now the patch is rather dead.
>
> Current the referred to patch applies just fine, to 2.6.15,
> and except for a conflict with the above mentioned patch which
> applies fine to 2.6.15-mm1 as well.

It conflicts with the x86-64 timer routing rewrite I did, but that's currently
on hold because it has some other issues. I can merge them later, no problem.

-Andi