First cut at support for booting a GPT labeled disk via the BIOS bootstrap

on i386 and amd64 machines.  The overall process is that /boot/pmbr lives
in the PMBR (similar to /boot/mbr for MBR disks) and is responsible for
locating and loading /boot/gptboot.  /boot/gptboot is similar to /boot/boot
except that it groks GPT rather than MBR + bsdlabel.  Unlike /boot/boot,
/boot/gptboot lives in its own dedicated GPT partition with a new
"FreeBSD boot" type.  This partition does not have a fixed size in that
/boot/pmbr will load the entire partition into the lower 640k.  However,
it is limited in that it can only be 545k.  That's still a lot better than
the current 7.5k limit for boot2 on MBR.  gptboot mostly acts just like
boot2 in that it reads /boot.config and loads up /boot/loader.  Some more
details:
- Include uuid_equal() and uuid_is_nil() in libstand.
- Add a new 'boot' command to gpt(8) which makes a GPT disk bootable using
  /boot/pmbr and /boot/gptboot.  Note that the disk must have some free
  space for the boot partition.
  - This required exposing the backend of the 'add' function as a
    gpt_add_part() function to the rest of gpt(8).  'boot' uses this to
    create a boot partition if needed.
- Don't cripple cgbase() in the UFS boot code for /boot/gptboot so that
  it can handle a filesystem > 1.5 TB.
- /boot/gptboot has a simple loader (gptldr) that doesn't do any I/O
  unlike boot1 since /boot/pmbr loads all of gptboot up front.  The
  C portion of gptboot (gptboot.c) has been repocopied from boot2.c.
  The primary changes are to parse the GPT to find a root filesystem
  and to use 64-bit disk addresses.  Currently gptboot assumes that the
  first UFS partition on the disk is the / filesystem, but this algorithm
  will likely be improved in the future.
- Teach the biosdisk driver in /boot/loader to understand GPT tables.
  GPT partitions are identified as 'disk0pX:' (e.g. disk0p2:) which is
  similar to the /dev names the kernel uses (e.g. /dev/ad0p2).
- Add a new "freebsd-boot" alias to g_part() for the new boot UUID.

MFC after:	1 month
Discussed with:	marcel (some things might still change, but am committing
			what I have so far)

1 files changed, 3 insertions, 1 deletions

diff --git a/sys/sys/gpt.h b/sys/sys/gpt.h
index 0c5fb06..2afd4f2 100644
--- a/sys/sys/gpt.h
+++ b/sys/sys/gpt.h
@@ -84,6 +84,8 @@ struct gpt_ent {
 	{0x516e7cb8,0x6ecf,0x11d6,0x8f,0xf8,{0x00,0x02,0x2d,0x09,0x71,0x2b}}
 #define	GPT_ENT_TYPE_FREEBSD_ZFS	\
 	{0x516e7cba,0x6ecf,0x11d6,0x8f,0xf8,{0x00,0x02,0x2d,0x09,0x71,0x2b}}
+#define	GPT_ENT_TYPE_FREEBSD_BOOT	\
+	{0x83bd6b9d,0x7f41,0x11dc,0xbe,0x0b,{0x00,0x15,0x60,0xb8,0x4f,0x0f}}
 
 /*
  * The following are unused but documented here to avoid reuse.
@@ -95,7 +97,7 @@ struct gpt_ent {
 /*
  * Foreign partition types that we're likely to encounter. Note that Linux
  * apparently choose to share data partitions with MS. I don't what the
- * advantage might be. I can see how sharing swap partitions is advantaous
+ * advantage might be. I can see how sharing swap partitions is advantageous
  * though.
  */
 #define	GPT_ENT_TYPE_MS_RESERVED	\