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SubjectRe: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2
On Sat, Feb 23, 2008 at 09:48:42PM -0800, Yinghai Lu wrote:
>
> quad core 8 socket system will have apic id lifting.the apic id range could
> be [4, 0x23]. and apic_is_clustered_box will think that need to three clusters
> and that is large than 2. So it is treated as clustered_box.

Ok I see you chose the quick hack over doing it properly ...

>
> and will get
>
> Marking TSC unstable due to TSCs unsynchronized
>
> even the CPUs have X86_FEATURE_CONSTANT_TSC set.

I doubt that will do the right thing on AMD based vSMP,
which also required the cluster check on AMD iirc.

Cc'ed Kiran/Shai. damage has already hit x86 tree I believe.

-Andi

diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index d8d03e0..7d8ffda 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -1180,9 +1180,19 @@ __cpuinit int apic_is_clustered_box(void)
{
int i, clusters, zeros;
unsigned id;
- u16 *bios_cpu_apicid = x86_bios_cpu_apicid_early_ptr;
+ u16 *bios_cpu_apicid;
DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
+ /*
+ * Some AMD box with quadcore cpu and 8 sockets apicid
+ * will be [4, 0x23] or [8, 0x27] could be thought to
+ * have three apic_clusters. So go out early.
+ */
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+ return 0;



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