doc/usage/cmd/gpt.rst

.. SPDX-License-Identifier: GPL-2.0+

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 setenv <interface> <dev> <partition name>
    gpt swap <interface> <dev> <name1> <name2>
    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 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 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 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

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