[PATCH] 2.4.23-rc1: cpu_sibling_map fix

[James Cleverdon]

On summit-based machines the cpu_sibling_map data has been hosed for some 
time.  I found out why in Intel's IA-32 Software Deveveopers' Manual Vol 2 
under CPUID.  Looks like the value that cpuid returns is the one latched at 
reset, and doesn't reflect any changes made by the BIOS later:

	* Local APIC ID (high byte of EBX)--this number is the 8-bit ID that is
	  assigned to the local APIC on the processor during power up. This field
	  was introduced in the Pentium 4 processor.

Also, the code in init_intel was a bit overdesigned.  Until Intel releases a 
chip with a non-power-of-2 sibling count on it, there's no point in all that 
bit bashing.


diff -pru 2.4.23-rc1/arch/i386/kernel/setup.c rc1/arch/i386/kernel/setup.c
--- 2.4.23-rc1/arch/i386/kernel/setup.c	2003-11-11 18:09:57.000000000 -0800
+++ rc1/arch/i386/kernel/setup.c	2003-11-12 15:18:44.000000000 -0800
@@ -2461,8 +2461,6 @@ static void __init init_intel(struct cpu
 		extern	int phys_proc_id[NR_CPUS];
 		
 		u32 	eax, ebx, ecx, edx;
-		int 	index_lsb, index_msb, tmp;
-		int	initial_apic_id;
 		int 	cpu = smp_processor_id();
 
 		cpuid(1, &eax, &ebx, &ecx, &edx);
@@ -2471,11 +2469,10 @@ static void __init init_intel(struct cpu
 		if (smp_num_siblings == 1) {
 			printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
 		} else if (smp_num_siblings > 1 ) {
-			index_lsb = 0;
-			index_msb = 31;
 			/*
 			 * At this point we only support two siblings per
-			 * processor package.
+			 * processor package.  Assume will be power of 2 until
+			 * we learn otherwise.
 			 */
 #define NR_SIBLINGS	2
 			if (smp_num_siblings != NR_SIBLINGS) {
@@ -2483,20 +2480,7 @@ static void __init init_intel(struct cpu
 				smp_num_siblings = 1;
 				return;
 			}
-			tmp = smp_num_siblings;
-			while ((tmp & 1) == 0) {
-				tmp >>=1 ;
-				index_lsb++;
-			}
-			tmp = smp_num_siblings;
-			while ((tmp & 0x80000000 ) == 0) {
-				tmp <<=1 ;
-				index_msb--;
-			}
-			if (index_lsb != index_msb )
-				index_msb++;
-			initial_apic_id = ebx >> 24 & 0xff;
-			phys_proc_id[cpu] = initial_apic_id >> index_msb;
+			phys_proc_id[cpu] = hard_smp_processor_id() & ~(smp_num_siblings - 1);
 
 			printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
                                phys_proc_id[cpu]);
diff -pru 2.4.23-rc1/include/asm-i386/apicdef.h rc1/include/asm-i386/apicdef.h
--- 2.4.23-rc1/include/asm-i386/apicdef.h	2003-08-25 04:44:43.000000000 -0700
+++ rc1/include/asm-i386/apicdef.h	2003-11-12 16:32:54.000000000 -0800
@@ -11,8 +11,8 @@
 #define		APIC_DEFAULT_PHYS_BASE	0xfee00000
  
 #define		APIC_ID		0x20
-#define			APIC_ID_MASK		(0x0F<<24)
-#define			GET_APIC_ID(x)		(((x)>>24)&0x0F)
+#define			APIC_ID_MASK		(0xFFu<<24)
+#define			GET_APIC_ID(x)		(((unsigned)(x)>>24)&0xFF)
 #define		APIC_LVR	0x30
 #define			APIC_LVR_MASK		0xFF00FF
 #define			GET_APIC_VERSION(x)	((x)&0xFF)
diff -pru 2.4.23-rc1/arch/i386/kernel/setup.c rc1/arch/i386/kernel/setup.c
--- 2.4.23-rc1/arch/i386/kernel/setup.c	2003-11-11 18:09:57.000000000 -0800
+++ rc1/arch/i386/kernel/setup.c	2003-11-12 15:18:44.000000000 -0800
@@ -2461,8 +2461,6 @@ static void __init init_intel(struct cpu
 		extern	int phys_proc_id[NR_CPUS];
 		
 		u32 	eax, ebx, ecx, edx;
-		int 	index_lsb, index_msb, tmp;
-		int	initial_apic_id;
 		int 	cpu = smp_processor_id();
 
 		cpuid(1, &eax, &ebx, &ecx, &edx);
@@ -2471,11 +2469,10 @@ static void __init init_intel(struct cpu
 		if (smp_num_siblings == 1) {
 			printk(KERN_INFO  "CPU: Hyper-Threading is disabled\n");
 		} else if (smp_num_siblings > 1 ) {
-			index_lsb = 0;
-			index_msb = 31;
 			/*
 			 * At this point we only support two siblings per
-			 * processor package.
+			 * processor package.  Assume will be power of 2 until
+			 * we learn otherwise.
 			 */
 #define NR_SIBLINGS	2
 			if (smp_num_siblings != NR_SIBLINGS) {
@@ -2483,20 +2480,7 @@ static void __init init_intel(struct cpu
 				smp_num_siblings = 1;
 				return;
 			}
-			tmp = smp_num_siblings;
-			while ((tmp & 1) == 0) {
-				tmp >>=1 ;
-				index_lsb++;
-			}
-			tmp = smp_num_siblings;
-			while ((tmp & 0x80000000 ) == 0) {
-				tmp <<=1 ;
-				index_msb--;
-			}
-			if (index_lsb != index_msb )
-				index_msb++;
-			initial_apic_id = ebx >> 24 & 0xff;
-			phys_proc_id[cpu] = initial_apic_id >> index_msb;
+			phys_proc_id[cpu] = hard_smp_processor_id() & ~(smp_num_siblings - 1);
 
 			printk(KERN_INFO  "CPU: Physical Processor ID: %d\n",
                                phys_proc_id[cpu]);
diff -pru 2.4.23-rc1/include/asm-i386/apicdef.h rc1/include/asm-i386/apicdef.h
--- 2.4.23-rc1/include/asm-i386/apicdef.h	2003-08-25 04:44:43.000000000 -0700
+++ rc1/include/asm-i386/apicdef.h	2003-11-12 16:32:54.000000000 -0800
@@ -11,8 +11,8 @@
 #define		APIC_DEFAULT_PHYS_BASE	0xfee00000
  
 #define		APIC_ID		0x20
-#define			APIC_ID_MASK		(0x0F<<24)
-#define			GET_APIC_ID(x)		(((x)>>24)&0x0F)
+#define			APIC_ID_MASK		(0xFFu<<24)
+#define			GET_APIC_ID(x)		(((unsigned)(x)>>24)&0xFF)
 #define		APIC_LVR	0x30
 #define			APIC_LVR_MASK		0xFF00FF
 #define			GET_APIC_VERSION(x)	((x)&0xFF)