add CPUID probe

Just print vendor, Hypervisor...

boot/Makefile

@@ -5,7 +5,7 @@ PROG = boot
 SRCS = srt0.S gdt.S boot.c
 OBJS = srt0.o gdt.o boot.o
 
-ESRCS = pccon.c sricon.c print.c fmt.c a20.c time.c mem.c
+ESRCS = pccon.c sricon.c print.c fmt.c a20.c time.c mem.c cpu.c
 OBJS += $(ESRCS:.c=.o)
 
 include $(SDIR)/Makefile.inc

boot/boot.c

@@ -7,6 +7,7 @@ static void machdep(void);
 
 void (*probe1[])(void) = {
 	a20up, coninit, memprobe,
+	cpuidprobe,
 };
 void (*probe2[])(void) = {
 };

boot/cpu.c

@@ -0,0 +1,56 @@
+#include <u.h>
+#include "dat.h"
+#include "fn.h"
+
+#define EFLAG_ID	0x00200000
+#define	CPUID(code, a, b, c, d)				\
+	__asm volatile("cpuid"				\
+	    : "=a" (a), "=b" (b), "=c" (c), "=d" (d)	\
+	    : "a" (code))
+
+void*
+memset(void *dst, int v, int l)
+{
+	char *p = dst;
+	for(int i = 0; i < l; ++i)
+		*p++ = 0;
+	return dst;
+}
+
+void
+cpuidprobe(void)
+{
+	int canuse;
+	union{
+		struct{u32 a,b,d,c;};
+		char arr[16];
+	}r = {0,};	
+
+	__asm volatile("pushfl\n\t"
+		"popl %2\n\t"
+		"xorl %2, %0\n\t"	/* Invert ID sotred in EFLAGS */
+		"pushl %0\n\t"
+		"popfl\n\t"
+		"pushfl\n\t"
+		"popl %0\n\t"
+		"xorl %2, %0\n\t"
+		: "=r" (canuse)
+		: "0" (EFLAG_ID), "r" (0) /* "EFLAGS_ID" same location "canuse" */
+		: "cc");
+	if(canuse != EFLAG_ID){
+		print("cpuid not available\n");
+		return;
+	}
+
+	// print vendor
+	CPUID(0x00, r.a, r.b, r.c, r.d);
+	print("CPU vender: %s\n", r.arr+4);
+	// Is running on Hypervisor?	
+	// But nothing to do...
+	memset(&r, 0,sizeof(r));
+	CPUID(0x01, r.a, r.b, r.c, r.d);
+	if(r.c & (1<<31)){
+		CPUID(1<<30, r.a, r.b, r.c, r.d);
+		print("Running on Hypervisor: %s\n", r.arr+4);
+	}
+}

boot/fn.h

@@ -29,6 +29,9 @@ void a20up(void);
 // mem.c
 void memprobe(void);
 
+// cpu.c
+void cpuidprobe(void);
+
 // time.c
 long getsecs(void);