CPU type detection

- sometimes the system needs to know precisely on what type of cpu is
  running. The cpu type id detected during arch specific
  initialization and kept in the machine structure for later use.

- as a side-effect the information is exported to userland

kernel/arch/i386/arch_system.c

@@ -304,8 +304,43 @@ PUBLIC void restore_fpu(struct proc *pr)
 	}
 }
 
+PRIVATE void cpu_identify(void)
+{
+	u32_t eax, ebx, ecx, edx;
+	
+	eax = 0;
+	_cpuid(&eax, &ebx, &ecx, &edx);
+
+	if (ebx == INTEL_CPUID_GEN_EBX && ecx == INTEL_CPUID_GEN_ECX &&
+			edx == INTEL_CPUID_GEN_EDX) {
+		machine.cpu_type.vendor = CPU_VENDOR_INTEL;
+		printf("Genuine Intel found\n");
+	} else if (ebx == AMD_CPUID_GEN_EBX && ecx == AMD_CPUID_GEN_ECX &&
+			edx == AMD_CPUID_GEN_EDX) {
+		machine.cpu_type.vendor = CPU_VENDOR_AMD;
+		printf("Authentic AMD found\n");
+	} else
+		machine.cpu_type.vendor = CPU_VENDOR_UNKNOWN;
+
+	if (eax == 0) 
+		return;
+
+	eax = 1;
+	_cpuid(&eax, &ebx, &ecx, &edx);
+
+	machine.cpu_type.family = (eax >> 8) & 0xf;
+	if (machine.cpu_type.family == 0xf)
+		machine.cpu_type.family += (eax >> 20) & 0xff;
+	machine.cpu_type.model = (eax >> 4) & 0xf;
+	if (machine.cpu_type.model == 0xf || machine.cpu_type.model == 0x6)
+		machine.cpu_type.model += ((eax >> 16) & 0xf) << 4 ;
+	machine.cpu_type.stepping = eax & 0xf;
+}
+
 PUBLIC void arch_init(void)
 {
+	cpu_identify();
+
 #ifdef CONFIG_APIC
 	/*
 	 * this is setting kernel segments to cover most of the phys memory. The

kernel/arch/i386/include/archconst.h

@@ -153,6 +153,10 @@
 #define AMD_CPUID_GEN_EDX	0x69746e65 /* ASCII value of "enti" */
 #define AMD_CPUID_GEN_ECX	0x444d4163 /* ASCII value of "cAMD" */
 
+#define CPU_VENDOR_INTEL	0
+#define CPU_VENDOR_AMD		2
+#define CPU_VENDOR_UNKNOWN	0xff
+
 /* fpu context should be saved in 16-byte aligned memory */
 #define FPUALIGN		16