diff -r 81c9213b3d39 tools/firmware/hvmloader/acpi/build.c
--- a/tools/firmware/hvmloader/acpi/build.c	Tue Nov 28 18:41:42 2006
+++ b/tools/firmware/hvmloader/acpi/build.c	Tue Nov 28 23:09:29 2006
@@ -32,6 +32,24 @@
 extern unsigned char AmlCode[];
 extern int DsdtLen;
 
+static int
+_memcmp(const void *s1, const void *s2, unsigned n)
+{
+    unsigned i;
+    uint8_t *p1 = (uint8_t *) s1;
+    uint8_t *p2 = (uint8_t *) s2;
+
+    for ( i = 0; i < n; i++ )
+    {
+        if ( p1[i] < p2[i] )
+            return -1;
+        else if ( p1[i] > p2[i] )
+            return 1;
+    }
+
+    return 0;
+}
+
 static void set_checksum(
     void *table, uint32_t checksum_offset, uint32_t length)
 {
@@ -126,7 +144,7 @@
     }
 
     /* TPM TCPA and SSDT. */
-    if ( memcmp((char *)0xFED40F00, tis_did_vid_rid,
+    if (_memcmp((char *)0xFED40F00, tis_did_vid_rid,
                 sizeof(tis_did_vid_rid)) == 0 ) /* Probe for TIS interface. */
     {
         memcpy(&buf[offset], AmlCode_TPM, sizeof(AmlCode_TPM));