+/*
+ * The NOPL instruction is supposed to exist on all CPUs with
+ * family >= 6, unfortunately, that's not true in practice because
+ * of early VIA chips and (more importantly) broken virtualizers that
+ * are not easy to detect. Hence, probe for it based on first
+ * principles.
+ *
+ * Note: no 64-bit chip is known to lack these, but put the code here
+ * for consistency with 32 bits, and to make it utterly trivial to
+ * diagnose the problem should it ever surface.
+ */
+static void __cpuinit detect_nopl(struct cpuinfo_x86 *c)
+{
+ const u32 nopl_signature = 0x888c53b1; /* Random number */
+ u32 has_nopl = nopl_signature;
+
+ clear_cpu_cap(c, X86_FEATURE_NOPL);
+ if (c->x86 >= 6) {
+ asm volatile("\n"
+ "1: .byte 0x0f,0x1f,0xc0\n" /* nopl %eax */
+ "2:\n"
+ " .section .fixup,\"ax\"\n"
+ "3: xor %0,%0\n"
+ " jmp 2b\n"
+ " .previous\n"
+ _ASM_EXTABLE(1b,3b)
+ : "+a" (has_nopl));
+
+ if (has_nopl == nopl_signature)
+ set_cpu_cap(c, X86_FEATURE_NOPL);
+ }
+}
+