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.. SPDX-License-Identifier: GPL-2.0+:
.. index::
single: bootmeth (command)
bootmeth command
================
Synopsis
--------
::
bootmeth list [-a] - list selected bootmeths (-a for all)
bootmeth order "[<bm> ...]" - select the order of bootmeths
bootmeth set <bootmeth> <property> <value> - set optional property
Description
-----------
The `bootmeth` command is used to manage bootmeths. It can list them and change
the order in which they are used.
See :doc:`/develop/bootstd/index` for more information.
.. _bootmeth_order:
bootmeth order
~~~~~~~~~~~~~~
Selects which bootmeths to use and the order in which they are invoked. When
scanning bootdevs, each bootmeth is tried in turn to see if it can find a valid
bootflow. You can use this command to adjust the order or even to omit some
boomeths.
The argument is a quoted list of bootmeths to use, by name. If global bootmeths
are included, they must be at the end, otherwise the scanning mechanism will not
work correctly.
bootmeth list
~~~~~~~~~~~~~
This lists the selected bootmeths, or all of them, if the `-a` flag is used.
The format looks like this:
===== === ================== =================================
Order Seq Name Description
===== === ================== =================================
0 0 extlinux Extlinux boot from a block device
1 1 efi EFI boot from an .efi file
2 2 pxe PXE boot from a network device
3 3 sandbox Sandbox boot for testing
glob 4 efi_mgr EFI bootmgr flow
===== === ================== =================================
The fields are as follows:
Order:
The order in which these bootmeths are invoked for each bootdev. If this
shows as a hyphen, then the bootmeth is not in the current ordering. If it
shows as 'glob', then this is a global bootmeth and should be at the end.
Seq:
The sequence number of the bootmeth, i.e. the normal ordering if none is set
Name:
Name of the bootmeth
Description:
A friendly description for the bootmeth
Example
-------
This shows listing bootmeths. All are present and in the normal order::
=> bootmeth list
Order Seq Name Description
----- --- ------------------ ------------------
0 0 distro Extlinux boot from a block device
1 1 efi EFI boot from an .efi file
2 2 pxe PXE boot from a network device
3 3 sandbox Sandbox boot for testing
4 4 efi_mgr EFI bootmgr flow
----- --- ------------------ ------------------
(5 bootmeths)
Now the order is changed, to include only two of them::
=> bootmeth order "sandbox distro"
=> bootmeth list
Order Seq Name Description
----- --- ------------------ ------------------
0 3 sandbox Sandbox boot for testing
1 0 distro Extlinux boot from a block device
----- --- ------------------ ------------------
(2 bootmeths)
The -a flag shows all bootmeths so you can clearly see which ones are used and
which are not::
=> bootmeth list -a
Order Seq Name Description
----- --- ------------------ ------------------
1 0 distro Extlinux boot from a block device
- 1 efi EFI boot from an .efi file
- 2 pxe PXE boot from a network device
0 3 sandbox Sandbox boot for testing
- 4 efi_mgr EFI bootmgr flow
----- --- ------------------ ------------------
(5 bootmeths)
bootmeth set
~~~~~~~~~~~~
Allows setting of bootmeth specific configuration. This allows finer grain
control over the boot process in specific instances.
Supported Configuration Options
-------------------------------
The following configuration options are currently supported:
======== =================== ====== ===============================
Property Supported Bootmeths Values Description
======== =================== ====== ===============================
fallback extlinux 0 | 1 Enable or disable fallback path
======== =================== ====== ===============================
Bootmeth set Example
--------------------
With the bootcount functionality enabled, when the bootlimit is reached, the
`altbootcmd` environment variable lists the command used for booting rather
than `bootcmd`. We can set the fallback configuration to cause the fallback
boot option to be preferred, to revert to a previous known working boot option
after a failed update for example. So if `bootcmd` is set to::
bootflow scan -lb
We would set "altbootcmd" to::
bootmeth set extlinux fallback 1; bootflow scan -lb
|
