Re: Are BSD partitions not supported?

["Grégoire Sutre" <gregoire.sutre@gmail.com>]

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On 05/19/2010 09:20 PM, Vladimir 'φ-coder/phcoder' Serbinenko wrote:

[snip]
-  delta = grub_partition_get_start (disk->partition);
+      delta = grub_le_to_cpu32 (whole_disk_be.offset);

As dicsussed on irc, this makes the delta completely dependent on the
c: entry of the disklabel, which could be bogus.

For instance, on NetBSD/i386, the system seems to work fine with random
entries for c: in the disk label stored on the disk. Even a null offset
is fine.  The in-core disklabel shown by the command disklabel (without
-r) is the correct one.  I give an example below, which was obtained on
system booted from wd0.

IMHO, the current code is better for the cases where the offsets in the
disklabel are absolute addresses, since it performs exactly the inverse
translation of the one done in grub_partition_get_start(), which AFAICS
is supposed to return the absolute address.

What we want here is to diverge from that code when the disklabel
offsets are relative.  I believe that testing whether c: has a null
offset gives the answer.  I changed Vladimir's second patch to do that.

We still have the problem that NetSBD uses c: for the whole-disk
partition on many ports (but it's d: on i386 and amd64), see [1].  For
those ports, the normal offset for c: is 0.  But maybe it's fair to
assume that, on those ports, the NetBSD slice is never embedded in
another partition?

Grégoire

[1] http://nxr.netbsd.org/source/s?defs=RAW_PART&project=/src

On-disk label
niagara# disklabel -r wd0
16 partitions:
#        size    offset     fstype
  a:    263088  10233405     4.2BSD
  b:   2097648  10496493       swap
  c:  82345673         0     unused
  d: 117210240         0     unused
.
.
.

-------------------------------------------------------------------------
In-core label

niagara# disklabel wd0
# /dev/rwd0d:
.
.
.
16 partitions:
#        size    offset     fstype
  a:    263088  10233405     4.2BSD
  b:   2097648  10496493       swap
  c:  58605120  10233405     unused
  d: 117210240         0     unused
.
.
.

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=== modified file 'include/grub/bsdlabel.h'
--- include/grub/bsdlabel.h	2010-02-06 17:43:37 +0000
+++ include/grub/bsdlabel.h	2010-05-23 09:21:04 +0000
@@ -63,6 +63,8 @@
 #define	GRUB_PC_PARTITION_OPENBSD_TYPE_NTFS	18
 #define	GRUB_PC_PARTITION_OPENBSD_TYPE_RAID	19
 
+#define GRUB_PC_PARTITION_BSD_LABEL_WHOLE_DISK_PARTITION 2
+
 /* The BSD partition entry.  */
 struct grub_partition_bsd_entry
 {

=== modified file 'partmap/bsdlabel.c'
--- partmap/bsdlabel.c	2010-03-26 14:44:13 +0000
+++ partmap/bsdlabel.c	2010-05-23 09:30:11 +0000
@@ -49,15 +49,37 @@
   if (label.magic != grub_cpu_to_le32 (GRUB_PC_PARTITION_BSD_LABEL_MAGIC))
     return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
 
+  /* A kludge for disklabels with relative offsets.  */
+  if (GRUB_PC_PARTITION_BSD_LABEL_WHOLE_DISK_PARTITION
+      < grub_cpu_to_le16 (label.num_partitions))
+    {
+      struct grub_partition_bsd_entry whole_disk_be;
+
+      pos = sizeof (label) + GRUB_PC_PARTITION_BSD_LABEL_SECTOR
+	* GRUB_DISK_SECTOR_SIZE + sizeof (struct grub_partition_bsd_entry)
+	* GRUB_PC_PARTITION_BSD_LABEL_WHOLE_DISK_PARTITION;
+
+      if (grub_disk_read (disk, pos / GRUB_DISK_SECTOR_SIZE,
+			  pos % GRUB_DISK_SECTOR_SIZE, sizeof (whole_disk_be),
+			  &whole_disk_be))
+	return grub_errno;
+
+      if (grub_le_to_cpu32 (whole_disk_be.offset) == 0)
+	delta = 0;
+    }
+
   pos = sizeof (label) + GRUB_PC_PARTITION_BSD_LABEL_SECTOR
     * GRUB_DISK_SECTOR_SIZE;
 
   for (p.number = 0;
        p.number < grub_cpu_to_le16 (label.num_partitions);
-       p.number++)
+       p.number++, pos += sizeof (struct grub_partition_bsd_entry))
     {
       struct grub_partition_bsd_entry be;
 
+      if (p.number == GRUB_PC_PARTITION_BSD_LABEL_WHOLE_DISK_PARTITION)
+	continue;
+
       p.offset = pos / GRUB_DISK_SECTOR_SIZE;
       p.index = pos % GRUB_DISK_SECTOR_SIZE;
 
@@ -68,11 +90,9 @@
       p.len = grub_le_to_cpu32 (be.size);
       p.partmap = &grub_bsdlabel_partition_map;
 
-      if (be.fs_type != GRUB_PC_PARTITION_BSD_TYPE_UNUSED)
+      if (p.len != 0)
 	if (hook (disk, &p))
 	  return grub_errno;
-
-      pos += sizeof (struct grub_partition_bsd_entry);
     }
 
   return GRUB_ERR_NONE;