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, 4 insertions, 1 deletions

diff --git a/arch/x86/kernel/apic_32.c b/arch/x86/kernel/apic_32.c
index c304759f0834..954d67931a50 100644
--- a/arch/x86/kernel/apic_32.c
+++ b/arch/x86/kernel/apic_32.c
@@ -1518,6 +1518,9 @@ void __cpuinit generic_processor_info(int apicid, int version)
                  */
                 cpu = 0;
 
+        if (apicid > max_physical_apicid)
+                max_physical_apicid = apicid;
+
         /*
          * Would be preferable to switch to bigsmp when CONFIG_HOTPLUG_CPU=y
          * but we need to work other dependencies like SMP_SUSPEND etc
@@ -1525,7 +1528,7 @@ void __cpuinit generic_processor_info(int apicid, int version)
          * if (CPU_HOTPLUG_ENABLED || num_processors > 8)
          *       - Ashok Raj <ashok.raj@intel.com>
          */
-        if (num_processors > 8) {
+        if (max_physical_apicid >= 8) {
                 switch (boot_cpu_data.x86_vendor) {
                 case X86_VENDOR_INTEL:
                         if (!APIC_XAPIC(version)) {