? commands/i386/pc/drivemap.c
Index: conf/i386-pc.mk
===================================================================
RCS file: /sources/grub/grub2/conf/i386-pc.mk,v
retrieving revision 1.132
diff -u -r1.132 i386-pc.mk
--- conf/i386-pc.mk	30 May 2008 04:20:47 -0000	1.132
+++ conf/i386-pc.mk	5 Jun 2008 20:08:20 -0000
@@ -842,7 +842,7 @@
 	vbe.mod vbetest.mod vbeinfo.mod video.mod gfxterm.mod \
 	videotest.mod play.mod bitmap.mod tga.mod cpuid.mod serial.mod	\
 	ata.mod vga.mod memdisk.mod jpeg.mod png.mod pci.mod lspci.mod \
-	aout.mod _bsd.mod bsd.mod
+	aout.mod _bsd.mod bsd.mod drivemap.mod
 
 # For biosdisk.mod.
 biosdisk_mod_SOURCES = disk/i386/pc/biosdisk.c
@@ -2970,4 +2970,60 @@
 bsd_mod_CFLAGS = $(COMMON_CFLAGS)
 bsd_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+# For drivemap.mod.
+drivemap_mod_SOURCES = commands/i386/pc/drivemap.c
+CLEANFILES += drivemap.mod mod-drivemap.o mod-drivemap.c pre-drivemap.o drivemap_mod-commands_i386_pc_drivemap.o und-drivemap.lst
+ifneq ($(drivemap_mod_EXPORTS),no)
+CLEANFILES += def-drivemap.lst
+DEFSYMFILES += def-drivemap.lst
+endif
+MOSTLYCLEANFILES += drivemap_mod-commands_i386_pc_drivemap.d
+UNDSYMFILES += und-drivemap.lst
+
+drivemap.mod: pre-drivemap.o mod-drivemap.o
+	-rm -f $@
+	$(TARGET_CC) $(drivemap_mod_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@ $^
+	$(STRIP) --strip-unneeded -K grub_mod_init -K grub_mod_fini -R .note -R .comment $@
+
+pre-drivemap.o: $(drivemap_mod_DEPENDENCIES) drivemap_mod-commands_i386_pc_drivemap.o
+	-rm -f $@
+	$(TARGET_CC) $(drivemap_mod_LDFLAGS) $(TARGET_LDFLAGS) -Wl,-r,-d -o $@ drivemap_mod-commands_i386_pc_drivemap.o
+
+mod-drivemap.o: mod-drivemap.c
+	$(TARGET_CC) $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) $(drivemap_mod_CFLAGS) -c -o $@ $<
+
+mod-drivemap.c: moddep.lst genmodsrc.sh
+	sh $(srcdir)/genmodsrc.sh 'drivemap' $< > $@ || (rm -f $@; exit 1)
+
+ifneq ($(drivemap_mod_EXPORTS),no)
+def-drivemap.lst: pre-drivemap.o
+	$(NM) -g --defined-only -P -p $< | sed 's/^\([^ ]*\).*/\1 drivemap/' > $@
+endif
+
+und-drivemap.lst: pre-drivemap.o
+	echo 'drivemap' > $@
+	$(NM) -u -P -p $< | cut -f1 -d' ' >> $@
+
+drivemap_mod-commands_i386_pc_drivemap.o: commands/i386/pc/drivemap.c $(commands/i386/pc/drivemap.c_DEPENDENCIES)
+	$(TARGET_CC) -Icommands/i386/pc -I$(srcdir)/commands/i386/pc $(TARGET_CPPFLAGS)  $(TARGET_CFLAGS) $(drivemap_mod_CFLAGS) -MD -c -o $@ $<
+-include drivemap_mod-commands_i386_pc_drivemap.d
+
+CLEANFILES += cmd-drivemap_mod-commands_i386_pc_drivemap.lst fs-drivemap_mod-commands_i386_pc_drivemap.lst partmap-drivemap_mod-commands_i386_pc_drivemap.lst
+COMMANDFILES += cmd-drivemap_mod-commands_i386_pc_drivemap.lst
+FSFILES += fs-drivemap_mod-commands_i386_pc_drivemap.lst
+PARTMAPFILES += partmap-drivemap_mod-commands_i386_pc_drivemap.lst
+
+cmd-drivemap_mod-commands_i386_pc_drivemap.lst: commands/i386/pc/drivemap.c $(commands/i386/pc/drivemap.c_DEPENDENCIES) gencmdlist.sh
+	set -e; 	  $(TARGET_CC) -Icommands/i386/pc -I$(srcdir)/commands/i386/pc $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) $(drivemap_mod_CFLAGS) -E $< 	  | sh $(srcdir)/gencmdlist.sh drivemap > $@ || (rm -f $@; exit 1)
+
+fs-drivemap_mod-commands_i386_pc_drivemap.lst: commands/i386/pc/drivemap.c $(commands/i386/pc/drivemap.c_DEPENDENCIES) genfslist.sh
+	set -e; 	  $(TARGET_CC) -Icommands/i386/pc -I$(srcdir)/commands/i386/pc $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) $(drivemap_mod_CFLAGS) -E $< 	  | sh $(srcdir)/genfslist.sh drivemap > $@ || (rm -f $@; exit 1)
+
+partmap-drivemap_mod-commands_i386_pc_drivemap.lst: commands/i386/pc/drivemap.c $(commands/i386/pc/drivemap.c_DEPENDENCIES) genpartmaplist.sh
+	set -e; 	  $(TARGET_CC) -Icommands/i386/pc -I$(srcdir)/commands/i386/pc $(TARGET_CPPFLAGS) $(TARGET_CFLAGS) $(drivemap_mod_CFLAGS) -E $< 	  | sh $(srcdir)/genpartmaplist.sh drivemap > $@ || (rm -f $@; exit 1)
+
+
+drivemap_mod_CFLAGS = $(COMMON_CFLAGS)
+drivemap_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 include $(srcdir)/conf/common.mk
Index: conf/i386-pc.rmk
===================================================================
RCS file: /sources/grub/grub2/conf/i386-pc.rmk,v
retrieving revision 1.119
diff -u -r1.119 i386-pc.rmk
--- conf/i386-pc.rmk	30 May 2008 04:20:47 -0000	1.119
+++ conf/i386-pc.rmk	5 Jun 2008 20:08:21 -0000
@@ -319,4 +319,9 @@
 bsd_mod_CFLAGS = $(COMMON_CFLAGS)
 bsd_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+# For drivemap.mod.
+drivemap_mod_SOURCES = commands/i386/pc/drivemap.c
+drivemap_mod_CFLAGS = $(COMMON_CFLAGS)
+drivemap_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 include $(srcdir)/conf/common.mk
Index: include/grub/loader.h
===================================================================
RCS file: /sources/grub/grub2/include/grub/loader.h,v
retrieving revision 1.9
diff -u -r1.9 loader.h
--- include/grub/loader.h	21 Jul 2007 23:32:22 -0000	1.9
+++ include/grub/loader.h	5 Jun 2008 20:08:21 -0000
@@ -37,6 +37,19 @@
 /* Unset current loader, if any.  */
 void EXPORT_FUNC(grub_loader_unset) (void);
 
+typedef struct hooklist_node *grub_preboot_hookid;
+
+/* Register a function to be called before the boot hook. Returns an id that
+   can be later used to unregister the preboot (i.e. if module unloaded). If
+   abort_on_error is set, the boot sequence will abort if any of the registered
+   functions return anything else than GRUB_ERR_NONE */
+grub_preboot_hookid EXPORT_FUNC(grub_loader_register_preboot)
+           (grub_err_t (*hook) (void), int abort_on_error); 
+
+/* Unregister a preboot hook by the id returned by loader_register_preboot.
+   This functions becomes a no-op if no such function is registered */
+void EXPORT_FUNC(grub_loader_unregister_preboot) (grub_preboot_hookid id);
+
 /* Call the boot hook in current loader. This may or may not return,
    depending on the setting by grub_loader_set.  */
 grub_err_t EXPORT_FUNC(grub_loader_boot) (void);
Index: include/grub/i386/loader.h
===================================================================
RCS file: /sources/grub/grub2/include/grub/i386/loader.h,v
retrieving revision 1.4
diff -u -r1.4 loader.h
--- include/grub/i386/loader.h	30 Mar 2008 18:04:39 -0000	1.4
+++ include/grub/i386/loader.h	5 Jun 2008 20:08:21 -0000
@@ -31,6 +31,15 @@
 extern grub_addr_t EXPORT_VAR(grub_os_area_addr);
 extern grub_size_t EXPORT_VAR(grub_os_area_size);
 
+extern grub_uint32_t EXPORT_VAR(grub_drivemap_int13_oldhandler); /* realm far ptr = 2 * 16b */
+extern grub_uint16_t EXPORT_VAR(grub_drivemap_int13_size);  /* Size of the section to be copied */
+/* This is NOT a typo: we just want this "void" var in order to take its
+ * address with &var - used for relative addressing within the int13 handler */
+extern void EXPORT_VAR(grub_drivemap_int13_handler_base);
+extern void EXPORT_VAR(grub_drivemap_int13_mapstart);
+
+void EXPORT_FUNC(grub_drivemap_int13_handler)(void);
+
 grub_err_t EXPORT_FUNC(grub_linux_boot) (void);
 
 /* The asm part of the multiboot loader.  */
Index: kern/loader.c
===================================================================
RCS file: /sources/grub/grub2/kern/loader.c,v
retrieving revision 1.9
diff -u -r1.9 loader.c
--- kern/loader.c	21 Jul 2007 23:32:26 -0000	1.9
+++ kern/loader.c	5 Jun 2008 20:08:21 -0000
@@ -61,11 +61,78 @@
   grub_loader_loaded = 0;
 }
 
+struct hooklist_node
+{
+  grub_err_t (*hook) (void);
+  int abort_on_error;
+  struct hooklist_node *next;
+};
+
+static struct hooklist_node *preboot_hooks = 0;
+
+grub_preboot_hookid
+grub_loader_register_preboot(grub_err_t (*hook) (void), int abort_on_error)
+{
+  if (0 == hook)
+    {
+      grub_error (GRUB_ERR_BAD_ARGUMENT, "preboot hoook must not be null");
+      return 0;
+    }
+  grub_preboot_hookid newentry = grub_malloc (sizeof (struct hooklist_node));
+  if (!newentry)
+    {
+      grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot alloc a hookinfo structure");
+      return 0;
+    }
+  else
+    {
+      newentry->hook = hook;
+      newentry->abort_on_error = abort_on_error;
+      newentry->next = preboot_hooks;
+      preboot_hooks = newentry;
+      return newentry;
+    }
+}
+
+void
+grub_loader_unregister_preboot(grub_preboot_hookid id)
+{
+  if (0 == id)
+    return;
+  grub_preboot_hookid entry = 0, search = preboot_hooks, previous = 0;
+  while (search)
+    {
+      if (search == id)
+        {
+          entry = search;
+          break;
+        }
+      previous = search;
+      search = search->next;
+    }
+  if (entry) /* Found */
+    {
+      if (previous)
+        previous->next = entry->next;
+      else preboot_hooks = entry->next; /* Entry was head of list */
+      grub_free (entry);
+    }
+}
+
 grub_err_t
 grub_loader_boot (void)
 {
   if (! grub_loader_loaded)
     return grub_error (GRUB_ERR_NO_KERNEL, "no loaded kernel");
+  
+  grub_preboot_hookid entry = preboot_hooks;
+  while (entry)
+    {
+      grub_err_t retVal = entry->hook();
+      if (retVal != GRUB_ERR_NONE && entry->abort_on_error)
+        return retVal;
+      entry = entry->next;
+    }
 
   if (grub_loader_noreturn)
     grub_machine_fini ();
Index: kern/i386/loader.S
===================================================================
RCS file: /sources/grub/grub2/kern/i386/loader.S,v
retrieving revision 1.3
diff -u -r1.3 loader.S
--- kern/i386/loader.S	19 Feb 2008 16:40:44 -0000	1.3
+++ kern/i386/loader.S	5 Jun 2008 20:08:22 -0000
@@ -59,6 +59,142 @@
 VARIABLE(grub_linux_is_bzimage)
 	.long	0
 
+
+#define GRUB_DRIVEMAP_INT13H_OFFSET(x) ((x) - grub_drivemap_int13_handler_base)
+VARIABLE(grub_drivemap_int13_handler_base)  /* When deployed, this tag must be segment-aligned */
+VARIABLE(grub_drivemap_int13_oldhandler)
+  .word 0xdead, 0xbeef
+/* Drivemap module - INT 13h handler - BIOS HD map */
+/* Right now this function is just a passthrough to the old handler
+ * We need to use relative addressing, and with CS to top it all, since we
+ * must make as few changes to the registers as possible. Pity we're not on
+ * amd64: rIP-relative addressing would make life easier here.
+ */
+.code16
+FUNCTION(grub_drivemap_int13_handler)
+  push %bp
+  mov %sp, %bp
+  push %ax  /* We'll need it later to determine the used BIOS function */
+
+  /* DEBUG: print requested drive (DL) */
+  /*push %es
+  pushal
+  mov $4, %di
+  mov $0xb800, %bx
+  mov %bx, %es
+  
+  movb %dl, %bl
+  andb $0x0f, %bl
+  addb $0x30, %bl
+  shll $16, %ebx
+  movb %dl, %bl
+  shrb $4, %bl
+  addb $0x30, %bl
+  andl $0x00ff00ff, %ebx
+  orl $0x0f000f00, %ebx
+  movl %ebx, %es:(%di)
+  add $4, %di
+  popal
+  pop %es*/
+
+  /* Map the drive number (always in DL?) */
+  push %ax
+  push %bx
+  push %si
+  mov $GRUB_DRIVEMAP_INT13H_OFFSET(grub_drivemap_int13_size), %bx
+  xor %si, %si
+1:movw %cs:(%bx,%si), %ax
+  cmp %ah, %al
+  jz 3f /* DRV=DST => map end - drive not remapped, leave DL as-is */
+  cmp %dl, %al
+  jz 2f /* Found - drive remapped, modify DL */
+  add $2, %si
+  jmp 1b /* Not found, but more remaining, loop  */
+2:mov %ah, %dl
+3:pop %si
+  pop %bx
+  xchgw %ax, -4(%bp) /* Recover the old AX and save the map entry for later */
+  
+  /* DEBUG: print map entry DRV (AL) and DST (AH) */  
+  /*push %es
+  pushal
+  mov $8, %di
+  mov $0xb800, %bx
+  mov %bx, %es
+  
+  movb -4(%bp), %bl
+  andb $0x0f, %bl
+  addb $0x30, %bl
+  shll $16, %ebx
+  movb -4(%bp), %bl
+  shrb $4, %bl
+  addb $0x30, %bl
+  andl $0x00ff00ff, %ebx
+  orl $0x0f000f00, %ebx
+  movl %ebx, %es:(%di)
+  add $4, %di
+   
+  movb -3(%bp), %bl
+  andb $0x0f, %bl
+  addb $0x30, %bl
+  shll $16, %ebx
+  movb -3(%bp), %bl
+  shrb $4, %bl
+  addb $0x30, %bl
+  andl $0x00ff00ff, %ebx
+  orl $0x0f000f00, %ebx
+  movl %ebx, %es:(%di)
+  add $4, %di
+
+  popal
+  pop %es*/
+
+  
+  push %bp  
+  /* Simulate interrupt call: push flags and do a far call in order to set
+   * the stack the way the old handler expects it so that its iret works */
+  push 6(%bp)
+  movw (%bp), %bp  /* Restore the caller BP (is this needed and/or sensible?) */
+  lcall *%cs:GRUB_DRIVEMAP_INT13H_OFFSET(grub_drivemap_int13_oldhandler)
+  pop %bp /* The pushed flags were removed by iret */
+  /* Set the saved flags to what the int13h handler returned */
+  push %ax
+  pushf
+  pop %ax
+  movw %ax, 6(%bp)
+  pop %ax
+
+  /* Reverse map any returned drive number if the data returned includes it.
+   * The only func that does this seems to be origAH = 0x08, but many BIOS
+   * refs say retDL = # of drives connected. However, the GRUB Legacy code
+   * treats this as the _drive number_ and "undoes" the remapping. Thus,
+   * this section has been disabled for testing if it's required */
+#  cmpb $0x08, -1(%bp) /* Caller's AH */
+#  jne 4f
+#  push %es
+#  pushal
+#  mov $0, %di
+#  mov $0xb800, %bx
+#  mov %bx, %es
+#  xchgw %ax, -4(%bp) /* Map entry used */
+#  cmp %ah, %al  /* DRV=DST => drive not remapped */
+#  je 4f
+#  mov %ah, %dl  /* Undo remap */
+
+4:mov %bp, %sp
+  pop %bp
+  iret
+/* This label MUST be at the end of the copied block, since the installer code
+ * reserves additional space for mappings at runtime and copies them over it */
+.align 2
+VARIABLE(grub_drivemap_int13_mapstart)
+  .space 0
+.code32 /* Copy stops here */
+VARIABLE(grub_drivemap_int13_size)
+  .word GRUB_DRIVEMAP_INT13H_OFFSET(grub_drivemap_int13_size)
+#undef GRUB_DRIVEMAP_INT13H_OFFSET
+
+
 FUNCTION(grub_linux_boot)
 	/* Must be done before zImage copy.  */
 	call	EXT_C(grub_dl_unload_all)