Re: Commit 34d76c41 causes linker errors on ia64 with NR_CPUS=4096
From: Jiri Kosina
Date: Mon Oct 19 2009 - 22:02:21 EST
On Sun, 18 Oct 2009, Jeff Mahoney wrote:
> Hi Peter -
>
> Commit 34d76c41 introduced the update_shares_data percpu, but it ends up
> causing problems on large ia64 machines. Specifically, ia64 is limited
> to 64k in percpu vars and with NR_CPUS=4096, that ends up being 32k by
> itself. It ends up causing link errors since that is how ia64 enforces
> the 64k limit.
>
> I can take a deeper look at finding a workable solution but thought I'd
> mention it in case you had ideas already.
I am adding some IA64 CCs, as the failure is solely caused by the ia64
percpu implementation/pagefault handler optimization which requires the
.percpu section area not be larger than 64k, which blows up with 34d76c41
and NR_CPUS high enoufh (due to introduction of percpu array being
size-dependent on NR_CPUS).
--
Jiri Kosina
SUSE Labs, Novell Inc.
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