Re: GPT on PC/BIOS computers

[Robert Millan <rmh@aybabtu.com>]

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On Sat, May 05, 2007 at 03:21:38PM +0200, Marco Gerards wrote:
> > I've looked into this, but I need some advice.  What's the simplest way to
> > obtain the corresponding grub_partition_t structure for a partition by knowing
> > its drive name?
> 
> You can use grub_partition_iterate.  Or open the disk and use
> ->partition.  You can read the name of the partitioning scheme.  The
> is also done in grub-setup.c, in the code you altered.

Patch attached.  Let me know if it's correct (I had my doubts about hardcoding
the the whole partition_map list in grub-probe.c, but then again I think safety
is more important).

-- 
Robert Millan

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2007-05-07  Robert Millan  <rmh@aybabtu.com>

	* util/i386/pc/grub-probe.c: Add `grub-probe -t ptable' parameter to
	determine partition table module.
	* util/i386/pc/grub-install.in: Use this feature to decide which
	partition module to load, instead of hardcoding pc and gpt.

diff -ur grub2-1.95+20070505.1.old/util/i386/pc/grub-install.in grub2-1.95+20070505.1/util/i386/pc/grub-install.in
--- grub2-1.95+20070505.1.old/util/i386/pc/grub-install.in	2007-05-07 10:53:25.000000000 +0200
+++ grub2-1.95+20070505.1/util/i386/pc/grub-install.in	2007-05-07 10:54:27.000000000 +0200
@@ -216,8 +216,16 @@
     exit 1
 fi
 
-# Typically, _chain, pc and gpt are required.
-modules="$modules $fs_module _chain pc gpt"
+# Then the partition table module.
+ptable_module=`$grub_probe --target=ptable --device-map=${device_map} ${grubdir}`
+if test "x$ptable_module" = x -a "x$modules" = x; then
+    echo "Auto-detection of a partition table module failed." 1>&2
+    echo "Please specify the module with the option \`--modules' explicitly." 1>&2
+    exit 1
+fi
+
+# _chain is often useful
+modules="$modules $fs_module $ptable_module _chain"
 
 $grub_mkimage --output=${grubdir}/core.img $modules || exit 1
 
diff -ur grub2-1.95+20070505.1.old/util/i386/pc/grub-probe.c grub2-1.95+20070505.1/util/i386/pc/grub-probe.c
--- grub2-1.95+20070505.1.old/util/i386/pc/grub-probe.c	2007-05-07 10:53:26.000000000 +0200
+++ grub2-1.95+20070505.1/util/i386/pc/grub-probe.c	2007-05-07 10:55:44.000000000 +0200
@@ -50,6 +50,7 @@
 #define PRINT_FS	0
 #define PRINT_DRIVE	1
 #define PRINT_DEVICE	2
+#define PRINT_PTABLE	3
 
 int print = PRINT_FS;
 
@@ -123,6 +124,23 @@
   if (! dev)
     grub_util_error ("%s", grub_errmsg);
 
+  if (print == PRINT_PTABLE)
+    {
+      if (strcmp (dev->disk->partition->partmap->name, "amiga_partition_map") == 0)
+        printf ("amiga\n");
+      else if (strcmp (dev->disk->partition->partmap->name, "apple_partition_map") == 0)
+        printf ("apple\n");
+      else if (strcmp (dev->disk->partition->partmap->name, "gpt_partition_map") == 0)
+        printf ("gpt\n");
+      else if (strcmp (dev->disk->partition->partmap->name, "pc_partition_map") == 0)
+        printf ("pc\n");
+      else if (strcmp (dev->disk->partition->partmap->name, "sun_partition_map") == 0)
+        printf ("sun\n");
+      else
+        grub_util_error ("Unknown partition table %s", dev->disk->partition->partmap->name);
+      goto end;
+    }
+
   fs = grub_fs_probe (dev);
   if (! fs)
     grub_util_error ("%s", grub_errmsg);
@@ -160,7 +178,8 @@
 Probe device information for a given path.\n\
 \n\
   -m, --device-map=FILE     use FILE as the device map [default=%s]\n\
-  -t, --target=(fs|drive|device)  print filesystem module, GRUB drive or system device [default=fs]\n\
+  -t, --target=(fs|drive|device|ptable)\n\
+                            print filesystem module, GRUB drive, system device or partition table module [default=fs]\n\
   -h, --help                display this message and exit\n\
   -V, --version             print version information and exit\n\
   -v, --verbose             print verbose messages\n\
@@ -204,6 +223,8 @@
 	      print = PRINT_DRIVE;
 	    else if (!strcmp (optarg, "device"))
 	      print = PRINT_DEVICE;
+	    else if (!strcmp (optarg, "ptable"))
+	      print = PRINT_PTABLE;
 	    else
 	      usage (1);
 	    break;