[PATCH] x86_64: add support for Intel dual-core detection and displaying

Appended patch adds the support for Intel dual-core detection and displaying
the core related information in /proc/cpuinfo.  

It adds two new fields "core id" and "cpu cores" to x86 /proc/cpuinfo and the
"core id" field for x86_64("cpu cores" field is already present in x86_64).

Number of processor cores in a die is detected using cpuid(4) and this is
documented in IA-32 Intel Architecture Software Developer's Manual (vol 2a)
(http://developer.intel.com/design/pentium4/manuals/index_new.htm#sdm_vol2a)

This patch also adds cpu_core_map similar to cpu_sibling_map.

Slightly hacked by AK.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/arch/i386/kernel/cpu/intel.c b/arch/i386/kernel/cpu/intel.c
index b8d847b850d..121aa2176e6 100644
--- a/arch/i386/kernel/cpu/intel.c
+++ b/arch/i386/kernel/cpu/intel.c
@@ -77,6 +77,27 @@ static void __init Intel_errata_workarounds(struct cpuinfo_x86 *c)
 }
 
 
+/*
+ * find out the number of processor cores on the die
+ */
+static int __init num_cpu_cores(struct cpuinfo_x86 *c)
+{
+        unsigned int eax;
+
+        if (c->cpuid_level < 4)
+                return 1;
+
+        __asm__("cpuid"
+                : "=a" (eax)
+                : "0" (4), "c" (0)
+                : "bx", "dx");
+
+        if (eax & 0x1f)
+                return ((eax >> 26) + 1);
+        else
+                return 1;
+}
+
 static void __init init_intel(struct cpuinfo_x86 *c)
 {
         unsigned int l2 = 0;
@@ -139,6 +160,8 @@ static void __init init_intel(struct cpuinfo_x86 *c)
         if ( p )
                 strcpy(c->x86_model_id, p);
         
+        c->x86_num_cores = num_cpu_cores(c);
+
         detect_ht(c);
 
         /* Work around errata */