[PATCH] AMD SMP capability sanity checking.

[Dave Jones]

In the wake of the recent fallout of "are Athlon XP's SMP capable or not",
the following patch adds some sanity checking to the SMP boot up code.
This code is based upon information from the folks at AMD. There are
no exceptions to these rules.

Before sending this to Linus, I want to make sure I didn't do something
dumb, like misplace a bracket, isolating a valid config.
It works on systems I've tested it on so far, but obviously there are
some combinations that are not tested.

Any "But my system is fine in SMP and isn't in the list" whinges won't
get it added to the list. The list is compiled from AMD approved
valid systems, added to by any system which reports itself as
multiprocessor capable in its cpu flags.

Note, this code will not stop you from continuing to use unsupported
configurations, but will..
a. Print a boot time warning.
b. Taint any oopses so that SMP problem oopses can be isolated easily.

I repeat, there is *no* loss of functionality.

Patch against 2.4.15pre5 follows.

regards,

Dave.

-- 
| Dave Jones.        http://www.codemonkey.org.uk
| SuSE Labs

diff -urN --exclude-from=/home/davej/.exclude linux-2.4.15-pre5/arch/i386/kernel/setup.c linux-2.4.15-pre5-dj/arch/i386/kernel/setup.c
--- linux-2.4.15-pre5/arch/i386/kernel/setup.c	Fri Nov 16 18:14:11 2001
+++ linux-2.4.15-pre5-dj/arch/i386/kernel/setup.c	Fri Nov 16 18:30:29 2001
@@ -2707,7 +2707,7 @@
 		/* AMD-defined */
 		NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 		NULL, NULL, NULL, "syscall", NULL, NULL, NULL, NULL,
-		NULL, NULL, NULL, NULL, NULL, NULL, "mmxext", NULL,
+		NULL, NULL, NULL, "mp", NULL, NULL, "mmxext", NULL,
 		NULL, NULL, NULL, NULL, NULL, "lm", "3dnowext", "3dnow",

 		/* Transmeta-defined */
diff -urN --exclude-from=/home/davej/.exclude linux-2.4.15-pre5/arch/i386/kernel/smpboot.c linux-2.4.15-pre5-dj/arch/i386/kernel/smpboot.c
--- linux-2.4.15-pre5/arch/i386/kernel/smpboot.c	Fri Oct  5 01:42:54 2001
+++ linux-2.4.15-pre5-dj/arch/i386/kernel/smpboot.c	Fri Nov 16 21:09:33 2001
@@ -30,10 +30,12 @@
  *		Tigran Aivazian	:	fixed "0.00 in /proc/uptime on SMP" bug.
  *	Maciej W. Rozycki	:	Bits for genuine 82489DX APICs
  *		Martin J. Bligh	: 	Added support for multi-quad systems
+ *		Dave Jones	:	Report invalid combinations of Athlon CPUs.
  */

 #include <linux/config.h>
 #include <linux/init.h>
+#include <linux/kernel.h>

 #include <linux/mm.h>
 #include <linux/kernel_stat.h>
@@ -156,6 +158,35 @@
 		 * Remember we have B step Pentia with bugs
 		 */
 		smp_b_stepping = 1;
+
+	/*
+	 * Certain Athlons might work (for various values of 'work') in SMP
+	 * but they are not certified as MP capable.
+	 */
+	if ((c->x86_vendor == X86_VENDOR_AMD) && (c->x86 == 6)) {
+
+		/* Athlon 660/661 is valid. */
+		if ((c->x86_model==6) && ((c->x86_mask==0) || (c->x86_mask==1)))
+			goto valid_athlon;
+
+		/* Duron 670 is valid */
+		if ((c->x86_model==7) && (c->x86_mask==0))
+			goto valid_athlon;
+
+		/* Athlon 662, Duron 671, and Athlon >model 7 have capability bit */
+		if (((c->x86_model==6) && (c->x86_mask>=2)) ||
+			((c->x86_model==7) && (c->x86_mask>=1)) ||
+			 (c->x86_model> 7))
+			if (cpu_has_mp)
+				goto valid_athlon;
+
+		/* If we get here, it's not a certified SMP capable AMD system. */
+		printk (KERN_INFO "WARNING: This combination of AMD processors is not suitable for SMP.\n");
+		tainted |= (1<<2);
+
+	}
+valid_athlon:
+
 }

 /*
diff -urN --exclude-from=/home/davej/.exclude linux-2.4.15-pre5/include/asm-i386/cpufeature.h linux-2.4.15-pre5-dj/include/asm-i386/cpufeature.h
--- linux-2.4.15-pre5/include/asm-i386/cpufeature.h	Mon Nov 13 05:55:50 2000
+++ linux-2.4.15-pre5-dj/include/asm-i386/cpufeature.h	Fri Nov 16 18:29:24 2001
@@ -46,6 +46,7 @@
 /* AMD-defined CPU features, CPUID level 0x80000001, word 1 */
 /* Don't duplicate feature flags which are redundant with Intel! */
 #define X86_FEATURE_SYSCALL	(1*32+11) /* SYSCALL/SYSRET */
+#define X86_FEATURE_MP		(1*32+19) /* MP Capable. */
 #define X86_FEATURE_MMXEXT	(1*32+22) /* AMD MMX extensions */
 #define X86_FEATURE_LM		(1*32+29) /* Long Mode (x86-64) */
 #define X86_FEATURE_3DNOWEXT	(1*32+30) /* AMD 3DNow! extensions */
diff -urN --exclude-from=/home/davej/.exclude linux-2.4.15-pre5/include/asm-i386/processor.h linux-2.4.15-pre5-dj/include/asm-i386/processor.h
--- linux-2.4.15-pre5/include/asm-i386/processor.h	Fri Nov 16 18:14:14 2001
+++ linux-2.4.15-pre5-dj/include/asm-i386/processor.h	Fri Nov 16 19:08:34 2001
@@ -90,6 +90,7 @@
 #define cpu_has_xmm	(test_bit(X86_FEATURE_XMM,  boot_cpu_data.x86_capability))
 #define cpu_has_fpu	(test_bit(X86_FEATURE_FPU,  boot_cpu_data.x86_capability))
 #define cpu_has_apic	(test_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability))
+#define cpu_has_mp (test_bit(X86_FEATURE_MP, boot_cpu_data.x86_capability))

 extern char ignore_irq13;

diff -urN --exclude-from=/home/davej/.exclude linux-2.4.15-pre5/kernel/panic.c linux-2.4.15-pre5-dj/kernel/panic.c
--- linux-2.4.15-pre5/kernel/panic.c	Sun Sep 30 19:26:08 2001
+++ linux-2.4.15-pre5-dj/kernel/panic.c	Fri Nov 16 20:46:17 2001
@@ -103,6 +103,10 @@
 /**
  *	print_tainted - return a string to represent the kernel taint state.
  *
+ *  'P' - Proprietory module has been loaded.
+ *  'F' - Module has been forcibly loaded.
+ *  'S' - SMP with CPUs not designed for SMP.
+ *
  *	The string is overwritten by the next call to print_taint().
  */

@@ -112,7 +116,8 @@
 	if (tainted) {
 		snprintf(buf, sizeof(buf), "Tainted: %c%c",
 			tainted & 1 ? 'P' : 'G',
-			tainted & 2 ? 'F' : ' ');
+			tainted & 2 ? 'F' : ' ',
+			tainted & 4 ? 'S' : ' ');
 	}
 	else
 		snprintf(buf, sizeof(buf), "Not tainted");