| .. 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 |