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Diffstat (limited to 'Documentation/user/bootchooser.rst')
| -rw-r--r-- | Documentation/user/bootchooser.rst | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/Documentation/user/bootchooser.rst b/Documentation/user/bootchooser.rst index 52aa595c74..7d7564b552 100644 --- a/Documentation/user/bootchooser.rst +++ b/Documentation/user/bootchooser.rst @@ -61,9 +61,15 @@ When booting, *bootchooser* starts the boot target with the highest ``priority`` has a non-zero ``remaining_attempts`` counter. With every start of a boot target the ``remaining_attempts`` counter of this boot target is decremented by one. This means every boot target's ``remaining_attempts`` counter reaches zero sooner or later and -the boot target won't be booted anymore. To prevent that, the ``remaining_attempts`` -counter must be reset to its default. There are different flags in the -*bootchooser* which control resetting the ``remaining_attempts`` counter, +the boot target won't be booted anymore. +This behavior assures that one can retry booting a target a limited number of +times to handle temporary issues (such as power outage) and optionally allows +booting a fallback in case of a permanent failure. +To indicate a successful boot, one must explicitly reset the remaining +attempts counter. See `Marking a Boot as Successful`_. + +To prevent ending up in an unbootable system after a number of failed boot +attempts, there is a also a built-in mechanism to reset the counters to their defaults, controlled by the ``global.bootchooser.reset_attempts`` variable. It holds a list of space-separated flags. Possible values are: @@ -74,12 +80,29 @@ list of space-separated flags. Possible values are: - ``all-zero``: The ``remaining_attempts`` counters of all enabled boot targets are reset when none of them has any ``remaining_attempts`` left. -Additionally the ``remaining_attempts`` counter can be reset manually using the -:ref:`bootchoser command <command_bootchooser>`. This allows for custom conditions -under which a system is marked as good. -In case only the booted system itself knows when it is in a good state, the -barebox-state tool from the dt-utils_ package can be used to reset the -``remaining_attempts`` counter from the running system. +Marking a Boot as Successful +############################ + +While the bootchooser algorithm handles attempts decrementation, retries and +selection of the right boot target itself, it cannot decide if the system +booted successfully on its own. + +In case only the booted system itself knows when it is in a good state, +it can report this to the bootchooser from Linux userspace using the +*barebox-state* tool from the dt-utils_ package.:: + + barebox-state -s bootstate.<target>.remaining_attemps <reset-value> + +If instead the bootchooser can detect a failed boot itself using the +:ref:`reset reason <reset_reason>` (WDG), one can mark the boot successful +using the barebox :ref:`bootchoser command <command_bootchooser>`:: + + bootchooser -s + +to mark the last boot successful. +This will reset the ``remaining_attempts`` counter of the *last chosen* slot to +its default value (``reset_attempts``). + .. _dt-utils: https://git.pengutronix.de/cgit/tools/dt-utils |