X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Fx86_cpu_features.c;h=3995413d6495b518181fcc2a843211f9a90b3fc7;hb=e4cdc80a6d033bb27ac0d1687ca32d0434673128;hp=aab200ffe5f2bb9b682592f8c4dee461234c2dbd;hpb=719a063c87e3abab99b0fb53ebc80223fbf33123;p=wimlib

diff --git a/src/x86_cpu_features.c b/src/x86_cpu_features.c
index aab200ff..3995413d 100644
--- a/src/x86_cpu_features.c
+++ b/src/x86_cpu_features.c
@@ -1,15 +1,27 @@
 /*
- * x86_cpu_features.c
+ * x86_cpu_features.c - feature detection for x86 processors
  *
- * Feature detection for x86 processors.
+ * The following copying information applies to this specific source code file:
  *
- * Author:	Eric Biggers
- * Year:	2015
+ * Written in 2015 by Eric Biggers <ebiggers3@gmail.com>
  *
- * The author dedicates this file to the public domain.
- * You can do whatever you want with this file.
+ * To the extent possible under law, the author(s) have dedicated all copyright
+ * and related and neighboring rights to this software to the public domain
+ * worldwide via the Creative Commons Zero 1.0 Universal Public Domain
+ * Dedication (the "CC0").
+ *
+ * This software is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the CC0 for more details.
+ *
+ * You should have received a copy of the CC0 along with this software; if not
+ * see <http://creativecommons.org/publicdomain/zero/1.0/>.
  */
 
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
 #include "wimlib/x86_cpu_features.h"
 
 #if defined(__i386__) || defined(__x86_64__)
@@ -47,7 +59,9 @@ read_xcr(u32 index)
 {
 	u32 edx, eax;
 
-	__asm__ ("xgetbv" : "=d" (edx), "=a" (eax) : "c" (index));
+	/* Execute the "xgetbv" instruction.  Old versions of binutils do not
+	 * recognize this instruction, so list the raw bytes instead.  */
+	__asm__ (".byte 0x0f, 0x01, 0xd0" : "=d" (edx), "=a" (eax) : "c" (index));
 
 	return ((u64)edx << 32) | eax;
 }