Change in coreboot[master]: [RFC]cpu/x86/mp.h: Guard mfence on pre SSE2 platforms

[Arthur Heymans (Code Review)]

Arthur Heymans has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/59766 )

Change subject: [RFC]cpu/x86/mp.h: Guard mfence on pre SSE2 platforms
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[RFC]cpu/x86/mp.h: Guard mfence on pre SSE2 platforms

Is this a good idea??

Change-Id: I376f86f4d7992344dd68374ba67ad3580070f4d8
Signed-off-by: Arthur Heymans 
---
M src/include/cpu/x86/mp.h
1 file changed, 3 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/66/59766/1

diff --git a/src/include/cpu/x86/mp.h b/src/include/cpu/x86/mp.h
index 934d217..f318277 100644
--- a/src/include/cpu/x86/mp.h
+++ b/src/include/cpu/x86/mp.h
@@ -13,7 +13,9 @@

static inline void mfence(void)
 {
-	__asm__ __volatile__("mfence\t\n": : :"memory");
+	/* mfence came with the introduction of SSE2. */
+	if (CONFIG(SSE2))
+		__asm__ __volatile__("mfence\t\n": : :"memory");
 }

/* The sequence of the callbacks are in calling order. */