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bootcount: clarify documentation

Browse source 
- Grammar fixes
- Clarify explanations

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
This commit is contained in:
Michael Opdenacker 2022-03-02 16:56:02 +01:00 committed by Heiko Schocher
parent e3c2042ae7
commit fc1383ae2b
2 changed files with 23 additions and 21 deletions
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34
doc/README.bootcount
View file

@ -3,14 +3,16 @@
Boot Count Limit Boot Count Limit
================ ================
This is enabled by CONFIG_BOOTCOUNT_LIMIT.
This allows to detect multiple failed attempts to boot Linux. This allows to detect multiple failed attempts to boot Linux.
After a power-on reset, "bootcount" variable will be initialized with 1, and After a power-on reset, the "bootcount" variable will be initialized to 1, and
each reboot will increment the value by 1. each reboot will increment the value by 1.
If, after a reboot, the new value of "bootcount" exceeds the value of If, after a reboot, the new value of "bootcount" exceeds the value of
"bootlimit", then instead of the standard boot action (executing the contents of "bootlimit", then instead of the standard boot action (executing the contents of
"bootcmd") an alternate boot action will be performed, and the contents of "bootcmd"), an alternate boot action will be performed, and the contents of
"altbootcmd" will be executed. "altbootcmd" will be executed.
If the variable "bootlimit" is not defined in the environment, the Boot Count If the variable "bootlimit" is not defined in the environment, the Boot Count
@ -18,18 +20,18 @@ Limit feature is disabled. If it is enabled, but "altbootcmd" is not defined,
then U-Boot will drop into interactive mode and remain there. then U-Boot will drop into interactive mode and remain there.
It is the responsibility of some application code (typically a Linux It is the responsibility of some application code (typically a Linux
application) to reset the variable "bootcount", thus allowing for more boot application) to reset the variable "bootcount" to 0 when the system booted
cycles. successfully, thus allowing for more boot cycles.
BOOTCOUNT_EXT CONFIG_BOOTCOUNT_EXT
------------- --------------------
This adds support for maintaining boot count in a file on an EXT filesystem. This adds support for maintaining boot count in a file on an EXT filesystem.
The file to use is define by: The file to use is defined by:
SYS_BOOTCOUNT_EXT_INTERFACE CONFIG_SYS_BOOTCOUNT_EXT_INTERFACE
SYS_BOOTCOUNT_EXT_DEVPART CONFIG_SYS_BOOTCOUNT_EXT_DEVPART
SYS_BOOTCOUNT_EXT_NAME CONFIG_SYS_BOOTCOUNT_EXT_NAME
The format of the file is: The format of the file is:
@ -42,10 +44,10 @@ u8 bootcount
u8 upgrade_available u8 upgrade_available
==== ================= ==== =================
To prevent unattended usage of "altbootcmd" the "upgrade_available" variable is To prevent unattended usage of "altbootcmd", the "upgrade_available" variable is
used. used.
If "upgrade_available" is 0, "bootcount" is not saved, if "upgrade_available" is If "upgrade_available" is 0, "bootcount" is not saved.
1 "bootcount" is save. If "upgrade_available" is 1, "bootcount" is saved.
So the Userspace Application must set the "upgrade_available" and "bootcount" So a userspace application should take care of setting the "upgrade_available"
variables to 0, if a boot was successfully. and "bootcount" variables to 0, if the system boots successfully.
This also prevents writes on all reboots. This also avoids writing the "bootcount" information on all reboots.

10
drivers/bootcount/Kconfig
View file

@ -68,15 +68,15 @@ config BOOTCOUNT_ENV
"bootcount" is stored in the environment. To prevent a "bootcount" is stored in the environment. To prevent a
saveenv on all reboots, the environment variable saveenv on all reboots, the environment variable
"upgrade_available" is used. If "upgrade_available" is "upgrade_available" is used. If "upgrade_available" is
0, "bootcount" is always 0, if "upgrade_available" is 0, "bootcount" is always 0. If "upgrade_available" is 1,
1 "bootcount" is incremented in the environment. "bootcount" is incremented in the environment.
So the Userspace Application must set the "upgrade_available" So the Userspace Application must set the "upgrade_available"
and "bootcount" variable to 0, if a boot was successfully. and "bootcount" variables to 0, if the system booted successfully.
config BOOTCOUNT_RAM config BOOTCOUNT_RAM
bool "Boot counter in RAM" bool "Boot counter in RAM"
help help
Store the bootcount in DRAM protected against against bit errors Store the bootcount in DRAM protected against bit errors
due to short power loss or holding a system in RESET. due to short power loss or holding a system in RESET.
config BOOTCOUNT_I2C config BOOTCOUNT_I2C
@ -166,7 +166,7 @@ config BOOTCOUNT_BOOTLIMIT
help help
Set the Maximum number of reboot cycles allowed without the boot Set the Maximum number of reboot cycles allowed without the boot
counter being cleared. counter being cleared.
If set to 0 do not set a boot limit in the environment. If set to 0, do not set a boot limit in the environment.
config BOOTCOUNT_ALEN config BOOTCOUNT_ALEN
int "I2C address length" int "I2C address length"