Re: [PATCH] - Increase MAX_APICS for very large x86_64 configs

From: Ingo Molnar
Date: Thu Jun 19 2008 - 06:10:54 EST



* Jack Steiner <steiner@xxxxxxx> wrote:

> Increase the maximum number of apics when running very large
> configurations. This patch has no affect on most systems.
>
> Signed-off-by: Jack Steiner <steiner@xxxxxxx>

applied to tip/x86/uv - thanks Jack.

> The patch has no effect on any 32-bit kernel. It adds ~4k to the size
> of 64-bit kernels but only if NR_CPUS > 255.
>
> This is a repost of an earlier patch (4/16) that was implicated in a
> random-qa failure. I have not been able to reproduce the failure using
> the same boot args & config. Best guess is that some other patch
> caused random data corruption & this patch was a victim.

i have just re-tested the previously failing config on tip/master:

http://redhat.com/~mingo/misc/config-Thu_Apr_17_10_17_14_CEST_2008.bad
http://people.redhat.com/mingo/tip.git/README

and the good news is that it does not crash on bootup anymore. Perhaps
one of Mike's fixes/improvements did the trick?

Nevertheless i'll keep an eye on this change and wont propagate it to
linux-next for a few days to make sure it's all robust on a wide range
of x86 testsystems.

Ingo
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