[PATCH] x86: sutomatically enable bigsmp when we have more than 8 CPUs

i386 generic subarchitecture requires explicit dmi strings or command line
to enable bigsmp mode.  The patch below removes that restriction, and uses
bigsmp as soon as it finds more than 8 logical CPUs, Intel processors and
xAPIC support.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/i386/kernel/mpparse.c b/arch/i386/kernel/mpparse.c
index ce838abb27d8..788efffa9930 100644
--- a/arch/i386/kernel/mpparse.c
+++ b/arch/i386/kernel/mpparse.c
@@ -65,6 +65,8 @@ int nr_ioapics;
 int pic_mode;
 unsigned long mp_lapic_addr;
 
+unsigned int def_to_bigsmp = 0;
+
 /* Processor that is doing the boot up */
 unsigned int boot_cpu_physical_apicid = -1U;
 /* Internal processor count */
@@ -213,6 +215,13 @@ static void __init MP_processor_info (struct mpc_config_processor *m)
                 ver = 0x10;
         }
         apic_version[m->mpc_apicid] = ver;
+        if ((num_processors > 8) &&
+            APIC_XAPIC(ver) &&
+            (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL))
+                def_to_bigsmp = 1;
+        else
+                def_to_bigsmp = 0;
+
         bios_cpu_apicid[num_processors - 1] = m->mpc_apicid;
 }