2007-01-23  Robert Millan  <address@hidden>

	* stage2/asm.S (check_64bit): New function.  Checks wether 64-bit mode
	is supported.
	* grub/asmstub.c (check_64bit): New function (stub).
	* stage2/shared.h: Declare check_64bit and is64bit.
	* stage2/common.c: Initialise is64bit with a check_64bit call.
	* stage2/builtins.c: New builtin (default64).  Behaves like default only
	on 64-bit systems (otherwise it's a no-op).

Index: grub/asmstub.c
===================================================================
RCS file: /sources/grub/grub/grub/asmstub.c,v
retrieving revision 1.86
diff -u -r1.86 asmstub.c
--- grub/asmstub.c	23 Apr 2006 10:10:52 -0000	1.86
+++ grub/asmstub.c	23 Jan 2007 21:15:14 -0000
@@ -1309,3 +1309,10 @@
 {
   return 1;
 }
+
+int
+check_64bit (void)
+{
+  /* Could be implemented using uname(), but it's useless in the simulator anyway */
+  return 0;
+}
Index: stage2/asm.S
===================================================================
RCS file: /sources/grub/grub/stage2/asm.S,v
retrieving revision 1.72
diff -u -r1.72 asm.S
--- stage2/asm.S	20 Jun 2004 13:48:46 -0000	1.72
+++ stage2/asm.S	23 Jan 2007 21:15:14 -0000
@@ -2365,3 +2365,67 @@
 gdtdesc:
 	.word	0x27			/* limit */
 	.long	gdt			/* addr */
+
+/*
+ * int check_64bit (void)
+ *
+ * Checks wether 64-bit mode is supported
+ *
+ * Stolen from a patch originaly intended for syslinux (http://syslinux.zytor.com/archives/2007-January/007832.html)
+ * Copyright (C) 2007 Byron Stanoszek <address@hidden>
+ *
+ * Adapted to AT&T syntax by Robert Millan <address@hidden>
+ */
+
+ENTRY(check_64bit)
+	pushl	%ebp
+	pushl	%ebx
+	pushl	%edx
+
+	/* Check if this CPU supports the CPUID command */
+	pushf
+	pushf
+	popl	%eax
+	movl	%eax, %ebx
+	xorl	$(1 << 21), %eax	// CPUID bit
+	pushl	%eax
+	popf
+	pushf
+	popl	%eax
+	popf				// Restore the original flags
+	xorl	%ebx, %eax
+	jz	is_32bit
+
+	/* Now check for the 64-bit flag in the CPU features byte ($0000_0001, edx)
+	This is bit 30 for Intel CPUs, and bit 29 for AMD CPUs */
+	movl	$0x00000000, %eax	// Find last Intel cpuid #
+	cpuid
+	cmpl	$0x00000000, %eax
+	je	test_amd
+	movl	$0x00000001, %eax	// Read Intel CPU flags
+	cpuid
+	btl	$30, %edx		// 64-bit if bit 30 is set
+	jc	is_64bit
+
+test_amd:
+	movl	$0x80000000, %eax	// Find last AMD cpuid #
+	cpuid
+	cmpl	$0x80000000, %eax
+	jbe	is_32bit
+	movl	$0x80000001, %eax	// Read AMD CPU flags
+	cpuid
+	btl	$29, %edx		// 64-bit if bit 29 is set
+	jnc	is_32bit
+
+is_64bit:
+	movl	$1, %eax
+	popl	%edx
+	popl	%ebx
+	popl	%ebp
+	ret
+is_32bit:
+	xorl	%eax, %eax
+	popl	%edx
+	popl	%ebx
+	popl	%ebp
+	ret
Index: stage2/builtins.c
===================================================================
RCS file: /sources/grub/grub/stage2/builtins.c,v
retrieving revision 1.152
diff -u -r1.152 builtins.c
--- stage2/builtins.c	21 Mar 2006 20:51:58 -0000	1.152
+++ stage2/builtins.c	23 Jan 2007 21:15:14 -0000
@@ -791,6 +791,23 @@
 #endif
 };
 
+/* default64 */
+static int
+default64_func (char *arg, int flags)
+{
+  if (is64bit)
+    return default_func (arg, flags);
+  else
+    return 0;
+}
+
+static struct builtin builtin_default64 =
+{
+  "default64",
+  default64_func,
+  BUILTIN_MENU,
+};
+
 
 #ifdef GRUB_UTIL
 /* device */
@@ -4807,6 +4824,7 @@
   &builtin_configfile,
   &builtin_debug,
   &builtin_default,
+  &builtin_default64,
 #ifdef GRUB_UTIL
   &builtin_device,
 #endif /* GRUB_UTIL */
Index: stage2/common.c
===================================================================
RCS file: /sources/grub/grub/stage2/common.c,v
retrieving revision 1.27
diff -u -r1.27 common.c
--- stage2/common.c	27 Mar 2004 17:02:54 -0000	1.27
+++ stage2/common.c	23 Jan 2007 21:15:14 -0000
@@ -39,6 +39,7 @@
 /* This saves the maximum size of extended memory (in KB).  */
 unsigned long extended_memory;
 #endif
+int is64bit;
 
 /*
  *  Error code stuff.
@@ -246,6 +247,8 @@
 
   saved_mem_upper = mbi.mem_upper;
 
+  is64bit = check_64bit ();
+
   /* Get the drive info.  */
   /* FIXME: This should be postponed until a Multiboot kernel actually
      requires it, because this could slow down the start-up
Index: stage2/shared.h
===================================================================
RCS file: /sources/grub/grub/stage2/shared.h,v
retrieving revision 1.100
diff -u -r1.100 shared.h
--- stage2/shared.h	2 May 2006 20:46:24 -0000	1.100
+++ stage2/shared.h	23 Jan 2007 21:15:14 -0000
@@ -995,6 +995,9 @@
 
 void init_bios_info (void);
 
+int check_64bit (void);
+extern int is64bit;
+
 #endif /* ASM_FILE */
 
 #endif /* ! GRUB_SHARED_HEADER */