x86: apic_is_clustered_box to indicate unsynched TSC's on multiboard vSMP systems
Indicate TSCs are unreliable as time sources if the platform is
a multi chassi ScaleMP vSMPowered machine.
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index 868ec1d..5362cfd 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -1209,7 +1209,7 @@
* will be [4, 0x23] or [8, 0x27] could be thought to
* vsmp box still need checking...
*/
- if (!is_vsmp_box() && (boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
+ if ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && !is_vsmp_box())
return 0;
bios_cpu_apicid = x86_bios_cpu_apicid_early_ptr;
@@ -1249,6 +1249,12 @@
++zeros;
}
+ /* ScaleMP vSMPowered boxes have one cluster per board and TSCs are
+ * not guaranteed to be synced between boards
+ */
+ if (is_vsmp_box() && clusters > 1)
+ return 1;
+
/*
* If clusters > 2, then should be multi-chassis.
* May have to revisit this when multi-core + hyperthreaded CPUs come