[PATCH] i386: cpu_detect extraction

Both lhype and Xen want to call the core of the x86 cpu detect code before
calling start_kernel.

(extracted from larger patch)

AK: folded in start_kernel header patch

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

arch/i386/kernel/cpu/common.c

@@ -236,29 +236,14 @@ static int __cpuinit have_cpuid_p(void)
 	return flag_is_changeable_p(X86_EFLAGS_ID);
 }
 
-/* Do minimum CPU detection early.
-   Fields really needed: vendor, cpuid_level, family, model, mask, cache alignment.
-   The others are not touched to avoid unwanted side effects.
-
-   WARNING: this function is only called on the BP.  Don't add code here
-   that is supposed to run on all CPUs. */
-static void __init early_cpu_detect(void)
+void __init cpu_detect(struct cpuinfo_x86 *c)
 {
-	struct cpuinfo_x86 *c = &boot_cpu_data;
-
-	c->x86_cache_alignment = 32;
-
-	if (!have_cpuid_p())
-		return;
-
 	/* Get vendor name */
 	cpuid(0x00000000, &c->cpuid_level,
 	      (int *)&c->x86_vendor_id[0],
 	      (int *)&c->x86_vendor_id[8],
 	      (int *)&c->x86_vendor_id[4]);
 
-	get_cpu_vendor(c, 1);
-
 	c->x86 = 4;
 	if (c->cpuid_level >= 0x00000001) {
 		u32 junk, tfms, cap0, misc;
@@ -275,6 +260,26 @@ static void __init early_cpu_detect(void)
 	}
 }
 
+/* Do minimum CPU detection early.
+   Fields really needed: vendor, cpuid_level, family, model, mask, cache alignment.
+   The others are not touched to avoid unwanted side effects.
+
+   WARNING: this function is only called on the BP.  Don't add code here
+   that is supposed to run on all CPUs. */
+static void __init early_cpu_detect(void)
+{
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	c->x86_cache_alignment = 32;
+
+	if (!have_cpuid_p())
+		return;
+
+	cpu_detect(c);
+
+	get_cpu_vendor(c, 1);
+}
+
 static void __cpuinit generic_identify(struct cpuinfo_x86 * c)
 {
 	u32 tfms, xlvl;

include/asm-i386/processor.h

@@ -20,6 +20,7 @@
 #include <linux/threads.h>
 #include <asm/percpu.h>
 #include <linux/cpumask.h>
+#include <linux/init.h>
 
 /* flag for disabling the tsc */
 extern int tsc_disable;
@@ -112,6 +113,8 @@ extern struct cpuinfo_x86 cpu_data[];
 extern	int cpu_llc_id[NR_CPUS];
 extern char ignore_fpu_irq;
 
+void __init cpu_detect(struct cpuinfo_x86 *c);
+
 extern void identify_cpu(struct cpuinfo_x86 *);
 extern void print_cpu_info(struct cpuinfo_x86 *);
 extern unsigned int init_intel_cacheinfo(struct cpuinfo_x86 *c);

include/linux/start_kernel.h

@@ -0,0 +1,12 @@
+#ifndef _LINUX_START_KERNEL_H
+#define _LINUX_START_KERNEL_H
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+/* Define the prototype for start_kernel here, rather than cluttering
+   up something else. */
+
+extern asmlinkage void __init start_kernel(void);
+
+#endif /* _LINUX_START_KERNEL_H */

init/main.c

@@ -29,6 +29,7 @@
 #include <linux/percpu.h>
 #include <linux/kmod.h>
 #include <linux/kernel_stat.h>
+#include <linux/start_kernel.h>
 #include <linux/security.h>
 #include <linux/workqueue.h>
 #include <linux/profile.h>