x86: introduce max_physical_apicid for bigsmp switching

a multi-socket test-system with 3 or 4 ioapics, when 4 dualcore cpus or
2 quadcore cpus installed, needs to switch to bigsmp or physflat.

CPU apic id is [4,11] instead of [0,7], and we need to check max apic
id instead of cpu numbers.

also add check for 32 bit when acpi is not compiled in or acpi=off.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index 54087f920f2f..1872555b98a3 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -1093,6 +1093,9 @@ void __cpuinit generic_processor_info(int apicid, int version)
                  */
                 cpu = 0;
         }
+        if (apicid > max_physical_apicid)
+                max_physical_apicid = apicid;
+
         /* are we being called early in kernel startup? */
         if (x86_cpu_to_apicid_early_ptr) {
                 u16 *cpu_to_apicid = x86_cpu_to_apicid_early_ptr;