part:efi: add bootable parameter in gpt command

The optional parameter bootable is added in gpt command to set the
partition attribute flag "Legacy BIOS bootable"

This flag is used in extlinux and so in with distro to select
the boot partition where is located the configuration file
(please check out doc/README.distro for details).

With this parameter, U-Boot can be used to create the boot partition
needed for device using distro.

example of use:

setenv partitions "name=u-boot,size=60MiB;name=boot,size=60Mib,bootable;\
                   name=rootfs,size=0"

> gpt write mmc 0 $partitions

> part list mmc 0

Partition Map for MMC device 0  --   Partition Type: EFI

Part	Start LBA	End LBA		Name
	Attributes
	Type GUID
	Partition GUID
  1	0x00000022	0x0001e021	"u-boot"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	cceb0b18-39cb-d547-9db7-03b405fa77d4
  2	0x0001e022	0x0003c021	"boot"
	attrs:	0x0000000000000004
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	d4981a2b-0478-544e-9607-7fd3c651068d
  3	0x0003c022	0x003a9fde	"rootfs"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	6d6c9a36-e919-264d-a9ee-bd00379686c7

> part list mmc 0 -bootable devplist

> printenv devplist

devplist=2

Then the distro scripts will search extlinux in partition 2
and not in the first partition.

Signed-off-by: Patrick Delaunay <patrick.delaunay73@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/doc/README.gpt b/doc/README.gpt
index db439f9f28..a6f6de6a0f 100644
--- a/doc/README.gpt
+++ b/doc/README.gpt
@@ -142,6 +142,10 @@ of the Primary.
 
 	   Attribute flags:
 	   Bit 0  - System partition
+	   Bit 1  - Hide from EFI
+	   Bit 2  - Legacy BIOS bootable
+	   Bit 48-63 - Defined and used by the individual partition type
+	   For Basic data partition :
 	   Bit 60 - Read-only
 	   Bit 62 - Hidden
 	   Bit 63 - Not mount
@@ -161,11 +165,21 @@ To restore GUID partition table one needs to:
    The fields 'name' and 'size' are mandatory for every partition.
    The field 'start' is optional.
 
+   If field 'size' of the last partition is 0, the partiton is extended
+   up to the end of the device.
+
    The fields 'uuid' and 'uuid_disk' are optional if CONFIG_RANDOM_UUID is
    enabled. A random uuid will be used if omitted or they point to an empty/
    non-existent environment variable. The environment variable will be set to
    the generated UUID.
 
+   The field 'bootable' is optional, it is used to mark the GPT partition
+   bootable (set attribute flags "Legacy BIOS bootable").
+     "name=u-boot,size=60MiB;name=boot,size=60Mib,bootable;name=rootfs,size=0"
+   It can be used to locate bootable disks with command
+   "part list <interface> <dev> -bootable <varname>",
+   please check out doc/README.distro for use.
+
 2. Define 'CONFIG_EFI_PARTITION' and 'CONFIG_CMD_GPT'
 
 3. From u-boot prompt type: