Index: mmap/i386/pc/mmap_helper.S
===================================================================
--- mmap/i386/pc/mmap_helper.S	(revisión: 2447)
+++ mmap/i386/pc/mmap_helper.S	(copia de trabajo)
@@ -48,9 +48,8 @@
 	popf
 	/* ljmp */
 	.byte	0xea
-VARIABLE (grub_machine_mmaphook_int15offset)
+VARIABLE (grub_machine_mmaphook_oldint15)
 	.word	0
-VARIABLE (grub_machine_mmaphook_int15segment)
 	.word	0
 
 e801:
Index: mmap/i386/pc/mmap.c
===================================================================
--- mmap/i386/pc/mmap.c	(revisión: 2447)
+++ mmap/i386/pc/mmap.c	(copia de trabajo)
@@ -25,17 +25,20 @@
 
 #define min(a,b) (((a) < (b)) ? (a) : (b))
 
+#define OFFSET_IN_ASM(addr) ( PTR_TO_UINT (addr) \
+                          - PTR_TO_UINT (&grub_machine_mmaphook_start) )
+
 static void *hooktarget = 0;
+/* Not a null pointer, the real mode IVT is actually at address 0:0 */
+static grub_machine_farptr *grub_machine_ivt = 0;
 
-extern grub_uint8_t grub_machine_mmaphook_start;
-extern grub_uint8_t grub_machine_mmaphook_end;
-extern grub_uint8_t grub_machine_mmaphook_int12;
-extern grub_uint8_t grub_machine_mmaphook_int15;
+extern const void grub_machine_mmaphook_start;
+extern const void grub_machine_mmaphook_end;
+extern const void grub_machine_mmaphook_int12;
+extern const void grub_machine_mmaphook_int15;
 
-static grub_uint16_t grub_machine_mmaphook_int12offset = 0;
-static grub_uint16_t grub_machine_mmaphook_int12segment = 0;
-extern grub_uint16_t grub_machine_mmaphook_int15offset;
-extern grub_uint16_t grub_machine_mmaphook_int15segment;
+static grub_machine_farptr grub_machine_mmaphook_oldint12;
+extern grub_machine_farptr grub_machine_mmaphook_oldint15;
 
 extern grub_uint16_t grub_machine_mmaphook_mmap_num;
 extern grub_uint16_t grub_machine_mmaphook_kblow;
@@ -73,9 +76,8 @@
 
   grub_dprintf ("mmap", "installing preboot handlers\n");
 
-  hookmmapcur = hookmmap = (struct grub_e820_mmap_entry *)
-    ((grub_uint8_t *) hooktarget + (&grub_machine_mmaphook_end
-				    - &grub_machine_mmaphook_start));
+  hookmmapcur = hookmmap = UINT_TO_PTR (PTR_TO_UINT (hooktarget)
+                                   + OFFSET_IN_ASM(&grub_machine_mmaphook_end));
 
   grub_mmap_iterate (fill_hook);
   grub_machine_mmaphook_mmap_num = hookmmapcur - hookmmap;
@@ -90,24 +92,23 @@
   *((grub_uint16_t *) 0x413) = grub_mmap_get_lower () >> 10;
 
   /* Save old interrupt handlers. */
-  grub_machine_mmaphook_int12offset = *((grub_uint16_t *) 0x48);
-  grub_machine_mmaphook_int12segment = *((grub_uint16_t *) 0x4a);
-  grub_machine_mmaphook_int15offset = *((grub_uint16_t *) 0x54);
-  grub_machine_mmaphook_int15segment = *((grub_uint16_t *) 0x56);
+  grub_machine_mmaphook_oldint12 = grub_machine_ivt[0x12];
+  grub_machine_mmaphook_oldint15 = grub_machine_ivt[0x15];
 
   grub_dprintf ("mmap", "hooktarget = %p\n", hooktarget);
 
   /* Install the interrupt handlers. */
   grub_memcpy (hooktarget, &grub_machine_mmaphook_start,
-	       &grub_machine_mmaphook_end - &grub_machine_mmaphook_start);
+	       OFFSET_IN_ASM(&grub_machine_mmaphook_end));
 
-  *((grub_uint16_t *) 0x4a) = PTR_TO_UINT32 (hooktarget) >> 4;
-  *((grub_uint16_t *) 0x56) = PTR_TO_UINT32 (hooktarget) >> 4;
-  *((grub_uint16_t *) 0x48) = &grub_machine_mmaphook_int12
-    - &grub_machine_mmaphook_start;
-  *((grub_uint16_t *) 0x54) = &grub_machine_mmaphook_int15
-    - &grub_machine_mmaphook_start;
+  void* newint12 = UINT_TO_PTR (PTR_TO_UINT (hooktarget)
+                                + OFFSET_IN_ASM(&grub_machine_mmaphook_int12));
+  void* newint15 = UINT_TO_PTR (PTR_TO_UINT (hooktarget)
+                                + OFFSET_IN_ASM(&grub_machine_mmaphook_int15));
 
+  grub_machine_ivt[0x12] = grub_machine_linear2real(newint12);
+  grub_machine_ivt[0x15] = grub_machine_linear2real(newint15);
+
   return GRUB_ERR_NONE;
 }
 
@@ -115,10 +116,8 @@
 preboot_rest (void)
 {
   /* Restore old interrupt handlers. */
-  *((grub_uint16_t *) 0x48) = grub_machine_mmaphook_int12offset;
-  *((grub_uint16_t *) 0x4a) = grub_machine_mmaphook_int12segment;
-  *((grub_uint16_t *) 0x54) = grub_machine_mmaphook_int15offset;
-  *((grub_uint16_t *) 0x56) = grub_machine_mmaphook_int15segment;
+  grub_machine_ivt[0x12] = grub_machine_mmaphook_oldint12;
+  grub_machine_ivt[0x15] = grub_machine_mmaphook_oldint15;
 
   return GRUB_ERR_NONE;
 }
@@ -161,12 +160,11 @@
       hooktarget = 0;
     }
 
-  hooksize = &grub_machine_mmaphook_end - &grub_machine_mmaphook_start
+  hooksize = OFFSET_IN_ASM(&grub_machine_mmaphook_end)
     + regcount * sizeof (struct grub_e820_mmap_entry);
   /* Allocate an integer number of KiB. */
   hooksize = ((hooksize - 1) | 0x3ff) + 1;
-  slots_available = (hooksize - (&grub_machine_mmaphook_end
-				 - &grub_machine_mmaphook_start))
+  slots_available = (hooksize - OFFSET_IN_ASM(&grub_machine_mmaphook_end))
     / sizeof (struct grub_e820_mmap_entry);
 
   reentry = 1;