[patch] genapic: default to physical mode on hotplug CPU kernels

From: Ingo Molnar
Date: Tue Nov 28 2006 - 15:26:09 EST



* Siddha, Suresh B <suresh.b.siddha@xxxxxxxxx> wrote:

> On Tue, Nov 28, 2006 at 07:33:46AM +0100, Ingo Molnar wrote:
> > - if (clusters <= 1 && max_cluster <= 8 && cluster_cnt[0] == max_cluster)
> > + if (max_apic < 8)
>
> Patch mostly looks good. Instead of checking for max_apic, can we use
> cpus_weight(cpu_possible_map) <= 8

ok - but i think it's still possible the BIOS tells us APIC IDs that are
larger than 7, even if there are fewer CPUs. So i think the patch below
should cover it. Agreed?

Ingo

-------------------->
From: Ingo Molnar <mingo@xxxxxxx>
Subject: [patch] genapic: default to physical mode on hotplug CPU kernels

default to physical mode on hotplug CPU kernels.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>

Index: linux/arch/x86_64/kernel/genapic.c
===================================================================
--- linux.orig/arch/x86_64/kernel/genapic.c
+++ linux/arch/x86_64/kernel/genapic.c
@@ -51,7 +51,7 @@ void __init clustered_apic_check(void)
max_apic = id;
}

- if (max_apic < 8)
+ if (max_apic < 8 && cpus_weight(cpu_possible_map) <= 8)
genapic = &apic_flat;
else
genapic = &apic_physflat;
-
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