[PATCH] hyper-threading info in /proc/cpuinfo

This adds hyper-threading information to /proc/cpuinfo, if relevant: the
physical processor id and the number of sibling units in this core.

The naming of the fields were debated a bit on lkml and the names below
offend the least number of people, do not break glibc, and are the same
as those in 2.4-ac.

This is in 2.4-ac, 2.5-mm, and vendor kernels from RedHat, SuSE, etc.

arch/i386/kernel/cpu/proc.c

@@ -17,6 +17,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 	 * applications want to get the raw CPUID data, they should access
 	 * /dev/cpu/<cpu_nr>/cpuid instead.
 	 */
+	extern int phys_proc_id[NR_CPUS];
 	static char *x86_cap_flags[] = {
 		/* Intel-defined */
 	        "fpu", "vme", "de", "pse", "tsc", "msr", "pae", "mce",
@@ -74,6 +75,12 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 	/* Cache size */
 	if (c->x86_cache_size >= 0)
 		seq_printf(m, "cache size\t: %d KB\n", c->x86_cache_size);
+#ifdef CONFIG_SMP
+	if (cpu_has_ht) {
+		seq_printf(m, "physical id\t: %d\n", phys_proc_id[n]);
+		seq_printf(m, "siblings\t: %d\n", smp_num_siblings);
+	}
+#endif
 	
 	/* We use exception 16 if we have hardware math and we've either seen it or the CPU claims it is internal */
 	fpu_exception = c->hard_math && (ignore_irq13 || cpu_has_fpu);

arch/i386/kernel/smpboot.c

@@ -58,7 +58,7 @@ static int __initdata smp_b_stepping;
 
 /* Number of siblings per CPU package */
 int smp_num_siblings = 1;
-int __initdata phys_proc_id[NR_CPUS]; /* Package ID of each logical CPU */
+int phys_proc_id[NR_CPUS]; /* Package ID of each logical CPU */
 
 /* Bitmask of currently online CPUs */
 unsigned long cpu_online_map;