From 8190bb688947a5ea03882a5c20cf3db968ca48b4 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Thu, 9 Jul 2015 10:51:55 +0200
Subject: [PATCH] add cpuid level check

only level >= 7 is able to determine AVX2
---
 hermit/arch/x86/include/asm/processor.h | 16 ++++++++--------
 hermit/arch/x86/kernel/processor.c      | 14 +++++++++++---
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/hermit/arch/x86/include/asm/processor.h b/hermit/arch/x86/include/asm/processor.h
index 05a13aa93..c4120e87a 100644
--- a/hermit/arch/x86/include/asm/processor.h
+++ b/hermit/arch/x86/include/asm/processor.h
@@ -61,19 +61,19 @@ extern "C" {
 #define CPU_FEATURE_SSE2		(1 << 26)
 
 // feature list 0x00000001 (ecx)
-#define CPU_FEATURE_SSE3				(1 << 9)
-#define CPU_FEATURE_FMA					(1 << 12)
+#define CPU_FEATURE_SSE3			(1 << 9)
+#define CPU_FEATURE_FMA				(1 << 12)
 #define CPU_FEATURE_SSE4_1			(1 << 19)
 #define CPU_FEATURE_SSE4_2			(1 << 20)
 #define CPU_FEATURE_X2APIC			(1 << 21)
-#define CPU_FEATURE_MOVBE				(1 << 22)
-#define CPU_FEATURE_XSAVE				(1 << 26)
+#define CPU_FEATURE_MOVBE			(1 << 22)
+#define CPU_FEATURE_XSAVE			(1 << 26)
 #define CPU_FEATURE_OSXSAVE			(1 << 27)
-#define CPU_FEATURE_AVX					(1 << 28)
-#define CPU_FEATURE_HYPERVISOR	(1 << 31)
+#define CPU_FEATURE_AVX				(1 << 28)
+#define CPU_FEATURE_HYPERVISOR			(1 << 31)
 
 // CPUID.80000001H:EDX feature list
-#define CPU_FEATURE_SYSCALL		(1 << 11)
+#define CPU_FEATURE_SYSCALL			(1 << 11)
 #define CPU_FEATURE_NX				(1 << 20)
 #define CPU_FEATURE_1GBHP			(1 << 26)
 #define CPU_FEATURE_LM				(1 << 29)
@@ -260,7 +260,7 @@ inline static uint32_t has_nx(void)
 }
 
 inline static uint32_t has_avx2(void) {
-	return (cpu_info.feature4 & CPU_FEATURE_AVX2);
+	return cpu_info.feature4 & CPU_FEATURE_AVX2;
 }
 /** @brief Read out time stamp counter
  *
diff --git a/hermit/arch/x86/kernel/processor.c b/hermit/arch/x86/kernel/processor.c
index 3601fe269..666acaab8 100644
--- a/hermit/arch/x86/kernel/processor.c
+++ b/hermit/arch/x86/kernel/processor.c
@@ -148,13 +148,18 @@ uint32_t detect_cpu_frequency(void)
 
 int cpu_detection(void) {
 	uint64_t xcr0;
-	uint32_t a=0, b=0, c=0, d=0;
+	uint32_t a=0, b=0, c=0, d=0, level = 0;
 	uint32_t family, model, stepping;
 	size_t cr4;
 	uint8_t first_time = 0;
 
 	if (!cpu_info.feature1) {
 		first_time = 1;
+
+		cpuid(0, &level, &b, &c, &d);
+		kprintf("cpuid level %d\n", level);
+
+		a = b = c = d = 0;
 		cpuid(1, &a, &b, &cpu_info.feature2, &cpu_info.feature1);
 
 		family   = (a & 0x00000F00) >> 8;
@@ -166,8 +171,11 @@ int cpu_detection(void) {
 		cpuid(0x80000001, &a, &b, &c, &cpu_info.feature3);
 		cpuid(0x80000008, &cpu_info.addr_width, &b, &c, &d);
 
-		a = b = c = d = 0;
-		cpuid(7, &a, &cpu_info.feature4, &c, &d);
+		/* Additional Intel-defined flags: level 0x00000007 */
+        	if (level >= 0x00000007) {
+			a = b = c = d = 0;
+			cpuid(7, &a, &cpu_info.feature4, &c, &d);
+		}
 	}
 
 	if (first_time) {