diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index f1af718519195efcaf7f6c02f4b8069154123f99..25581dcb280ea8d3a9c8840cd70fcc726e10b76f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -124,18 +124,25 @@ static inline int flag_is_changeable_p(u32 flag)
 {
 	u32 f1, f2;
 
-	asm("pushfl\n\t"
-	    "pushfl\n\t"
-	    "popl %0\n\t"
-	    "movl %0,%1\n\t"
-	    "xorl %2,%0\n\t"
-	    "pushl %0\n\t"
-	    "popfl\n\t"
-	    "pushfl\n\t"
-	    "popl %0\n\t"
-	    "popfl\n\t"
-	    : "=&r" (f1), "=&r" (f2)
-	    : "ir" (flag));
+	/*
+	 * Cyrix and IDT cpus allow disabling of CPUID
+	 * so the code below may return different results
+	 * when it is executed before and after enabling
+	 * the CPUID. Add "volatile" to not allow gcc to
+	 * optimize the subsequent calls to this function.
+	 */
+	asm volatile ("pushfl\n\t"
+		      "pushfl\n\t"
+		      "popl %0\n\t"
+		      "movl %0,%1\n\t"
+		      "xorl %2,%0\n\t"
+		      "pushl %0\n\t"
+		      "popfl\n\t"
+		      "pushfl\n\t"
+		      "popl %0\n\t"
+		      "popfl\n\t"
+		      : "=&r" (f1), "=&r" (f2)
+		      : "ir" (flag));
 
 	return ((f1^f2) & flag) != 0;
 }