diff -ur gpac.orig/extra_lib/include/gecko-sdk/nspr/include/md/_linux.h gpac/extra_lib/include/gecko-sdk/nspr/include/md/_linux.h
--- gpac.orig/extra_lib/include/gecko-sdk/nspr/include/md/_linux.h	2005-07-18 17:51:49.000000000 +0200
+++ gpac/extra_lib/include/gecko-sdk/nspr/include/md/_linux.h	2006-06-12 19:10:17.766003500 +0200
@@ -49,6 +49,8 @@
 #define _PR_SI_ARCHITECTURE "alpha"
 #elif defined(__ia64__)
 #define _PR_SI_ARCHITECTURE "ia64"
+#elif defined(__x86_64__)
+#define _PR_SI_ARCHITECTURE "x86-64"
 #elif defined(__mc68000__)
 #define _PR_SI_ARCHITECTURE "m68k"
 #elif defined(__sparc__)
@@ -109,6 +111,19 @@
 #define _MD_ATOMIC_SET                _PR_ia64_AtomicSet
 #endif
 
+#if defined(__x86_64__)
+#define _PR_HAVE_ATOMIC_OPS
+#define _MD_INIT_ATOMIC()
+extern PRInt32 _PR_x86_64_AtomicIncrement(PRInt32 *val);
+#define _MD_ATOMIC_INCREMENT          _PR_x86_64_AtomicIncrement
+extern PRInt32 _PR_x86_64_AtomicDecrement(PRInt32 *val);
+#define _MD_ATOMIC_DECREMENT          _PR_x86_64_AtomicDecrement
+extern PRInt32 _PR_x86_64_AtomicAdd(PRInt32 *ptr, PRInt32 val);
+#define _MD_ATOMIC_ADD                _PR_x86_64_AtomicAdd
+extern PRInt32 _PR_x86_64_AtomicSet(PRInt32 *val, PRInt32 newval);
+#define _MD_ATOMIC_SET                _PR_x86_64_AtomicSet
+#endif
+
 #define USE_SETJMP
 #if defined(__GLIBC__) && __GLIBC__ >= 2
 #define _PR_POLL_AVAILABLE
diff -ur gpac.orig/extra_lib/include/gecko-sdk/nspr/include/prcpucfg.h gpac/extra_lib/include/gecko-sdk/nspr/include/prcpucfg.h
--- gpac.orig/extra_lib/include/gecko-sdk/nspr/include/prcpucfg.h	2005-07-18 17:51:52.000000000 +0200
+++ gpac/extra_lib/include/gecko-sdk/nspr/include/prcpucfg.h	2006-06-12 19:09:24.586680000 +0200
@@ -347,6 +347,52 @@
 #define PR_BYTES_PER_WORD_LOG2  3
 #define PR_BYTES_PER_DWORD_LOG2 3
 
+#elif defined(__x86_64__)
+
+#define IS_LITTLE_ENDIAN 1
+#undef  IS_BIG_ENDIAN
+#define IS_64
+
+#define PR_BYTES_PER_BYTE   1
+#define PR_BYTES_PER_SHORT  2
+#define PR_BYTES_PER_INT    4
+#define PR_BYTES_PER_INT64  8
+#define PR_BYTES_PER_LONG   8
+#define PR_BYTES_PER_FLOAT  4
+#define PR_BYTES_PER_DOUBLE 8
+#define PR_BYTES_PER_WORD   8
+#define PR_BYTES_PER_DWORD  8
+
+#define PR_BITS_PER_BYTE    8
+#define PR_BITS_PER_SHORT   16
+#define PR_BITS_PER_INT     32
+#define PR_BITS_PER_INT64   64
+#define PR_BITS_PER_LONG    64
+#define PR_BITS_PER_FLOAT   32
+#define PR_BITS_PER_DOUBLE  64
+#define PR_BITS_PER_WORD    64
+
+#define PR_BITS_PER_BYTE_LOG2   3
+#define PR_BITS_PER_SHORT_LOG2  4
+#define PR_BITS_PER_INT_LOG2    5
+#define PR_BITS_PER_INT64_LOG2  6
+#define PR_BITS_PER_LONG_LOG2   6
+#define PR_BITS_PER_FLOAT_LOG2  5
+#define PR_BITS_PER_DOUBLE_LOG2 6
+#define PR_BITS_PER_WORD_LOG2   6
+
+#define PR_ALIGN_OF_SHORT   2
+#define PR_ALIGN_OF_INT     4
+#define PR_ALIGN_OF_LONG    8
+#define PR_ALIGN_OF_INT64   8
+#define PR_ALIGN_OF_FLOAT   4
+#define PR_ALIGN_OF_DOUBLE  8
+#define PR_ALIGN_OF_POINTER 8
+#define PR_ALIGN_OF_WORD    8
+
+#define PR_BYTES_PER_WORD_LOG2  3
+#define PR_BYTES_PER_DWORD_LOG2 3
+
 #elif defined(__mc68000__)
 
 #undef  IS_LITTLE_ENDIAN