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gpt command

Synopsis

gpt enumerate <interface> <dev>
gpt guid <interface> <dev> [<varname>]
gpt read <interface> <dev> [<varname>]
gpt rename <interface> <dev> <part> <name>
gpt repair <interface> <dev>
gpt set-bootable <interface> <dev> <partition list>
gpt setenv <interface> <dev> <partition name>
gpt swap <interface> <dev> <name1> <name2>
gpt transpose <interface> <dev> <part1> <part2>
gpt verify <interface> <dev> [<partition string>]
gpt write <interface> <dev> <partition string>

Description

The gpt command lets users read, create, modify, or verify the GPT (GUID Partition Table) partition layout.

Common arguments:

interface
interface for accessing the block device (mmc, sata, scsi, usb, ....)
dev
device number
partition string

Describes the GPT partition layout for a disk. The syntax is similar to the one used by the :doc:`mbr command <mbr>` command. The string contains one or more partition descriptors, each separated by a ";". Each descriptor contains one or more fields, with each field separated by a ",". Fields are either of the form "key=value" to set a specific value, or simple "flag" to set a boolean flag

The first descriptor can optionally be used to describe parameters for the whole disk with the following fields:

  • uuid_disk=UUID - Set the UUID for the disk

Partition descriptors can have the following fields:

  • name=<NAME> - The partition name, required
  • start=<BYTES> - The partition start offset in bytes, required
  • size=<BYTES> - The partition size in bytes or "-" to expand it to the whole free area
  • bootable - Set the legacy bootable flag
  • uuid=<UUID> - The partition UUID, optional if CONFIG_RANDOM_UUID=y is enabled
  • type=<UUID> - The partition type GUID, requires CONFIG_PARTITION_TYPE_GUID=y

If 'uuid' is not specified, but CONFIG_RANDOM_UUID is enabled, a random UUID will be generated for the partition

gpt enumerate

Sets the variable 'gpt_partition_list' to be a list of all the partition names on the device.

gpt guid

Report the GUID of a disk. If 'varname' is specified, the command will set the variable to the GUID, otherwise it will be printed out.

gpt read

Prints the current state of the GPT partition table. If 'varname' is specified, the variable will be filled with a partition string in the same format as a '<partition string>', suitable for passing to other 'gpt' commands. If the argument is omitted, a human readable description is printed out. CONFIG_CMD_GPT_RENAME=y is required.

gpt rename

Renames all partitions named 'part' to be 'name'. CONFIG_CMD_GPT_RENAME=y is required.

gpt repair

Repairs the GPT partition tables if it they become corrupted.

gpt set-bootable

Sets the bootable flag for all partitions in the table. If the partition name is in 'partition list' (separated by ','), the bootable flag is set, otherwise it is cleared. CONFIG_CMD_GPT_RENAME=y is required.

gpt setenv

The 'gpt setenv' command will set a series of environment variables with information about the partition named '<partition name>'. The variables are:

gpt_partition_addr
the starting offset of the partition in blocks as a hexadecimal number
gpt_partition_size
the size of the partition in blocks as a hexadecimal number
gpt_partition_name
the name of the partition
gpt_partition_entry
the partition number in the table, e.g. 1, 2, 3, etc.
gpt_partition_bootable
1 if the partition is marked as bootable, 0 if not

gpt swap

Changes the names of all partitions that are named 'name1' to be 'name2', and all partitions named 'name2' to be 'name1'. CONFIG_CMD_GPT_RENAME=y is required.

gpt transpose

Swaps the order of two partition table entries with indexes 'part1' and 'part2' in the partition table, but otherwise leaves the actual partition data untouched.

gpt verify

Sets return value $? to 0 (true) if the partition layout on the specified disk matches the one in the provided partition string, and 1 (false) if it does not match. If no partition string is specified, the command will check if the disk is partitioned or not.

gpt write

(Re)writes the partition table on the disk to match the provided partition string. It returns 0 on success or 1 on failure.

Configuration

To use the 'gpt' command you must specify CONFIG_CMD_GPT=y. To enable 'gpt read', 'gpt swap' and 'gpt rename', you must specify CONFIG_CMD_GPT_RENAME=y.

Examples

Create 6 partitions on a disk:

=> setenv gpt_parts 'uuid_disk=bec9fc2a-86c1-483d-8a0e-0109732277d7;
    name=boot,start=4M,size=128M,bootable,type=ebd0a0a2-b9e5-4433-87c0-68b6b72699c7,
    name=rootfs,size=3072M,type=0fc63daf-8483-4772-8e79-3d69d8477de4;
    name=system-data,size=512M,type=0fc63daf-8483-4772-8e79-3d69d8477de4;
    name=[ext],size=-,type=0fc63daf-8483-4772-8e79-3d69d8477de4;
    name=user,size=-,type=0fc63daf-8483-4772-8e79-3d69d8477de4;
    name=modules,size=100M,type=0fc63daf-8483-4772-8e79-3d69d8477de4;
    name=ramdisk,size=8M,type=0fc63daf-8483-4772-8e79-3d69d8477de4
=> gpt write mmc 0 $gpt_parts

Verify that the device matches the partition layout described in the variable $gpt_parts:

=> gpt verify mmc 0 $gpt_parts

Get the information about the partition named 'rootfs':

=> gpt setenv mmc 0 rootfs
=> echo ${gpt_partition_addr}
2000
=> echo ${gpt_partition_size}
14a000
=> echo ${gpt_partition_name}
rootfs
=> echo ${gpt_partition_entry}
2
=> echo ${gpt_partition_bootable}
0

Get the list of partition names on the disk:

=> gpt enumerate
=> echo ${gpt_partition_list}
boot rootfs system-data [ext] user modules ramdisk

Get the GUID for a disk:

=> gpt guid mmc 0
bec9fc2a-86c1-483d-8a0e-0109732277d7
=> gpt guid mmc gpt_disk_uuid
=> echo ${gpt_disk_uuid}
bec9fc2a-86c1-483d-8a0e-0109732277d7

Set the bootable flag for the 'boot' partition and clear it for all others:

=> gpt set-bootable mmc 0 boot

Swap the order of the 'boot' and 'rootfs' partition table entries:

=> gpt setenv mmc 0 rootfs
=> echo ${gpt_partition_entry}
2
=> gpt setenv mmc 0 boot
=> echo ${gpt_partition_entry}
1

=> gpt transpose mmc 0 1 2

=> gpt setenv mmc 0 rootfs
=> echo ${gpt_partition_entry}
1
=> gpt setenv mmc 0 boot
=> echo ${gpt_partition_entry}
2