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%SECTION0{name=UBootBootCountLimit}% Boot Count Limit The Open Source Development Labs _Carrier Grade Linux Requirements Definition_ version 2.0 (http://www.osdl.org/docs/carrier_grade_linux_requirements_definition___version_20_final_public_draft.pdf) contains the following requirement definition (ID PLT.4.0, p. 44): _CGL shall provide support for detecting a repeating reboot cycle due to recurring failures and will go to an offline state if this occurs._ This feature is available in U-Boot if you enable the ==CONFIG_BOOTCOUNT_LIMIT== configuration option. The implementation uses the following environment variables: *bootcount*:: This variable will be automatically created if it does not exist, and it will be updated at each reset of the processor. After a power-on reset, it will be initialized with *1*, and each reboot will increment the value by *1*. *bootlimit*:: If this variable exists, its contents are taken as the maximum number of reboot cycles allowed. *altbootcmd*:: 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 ==bootcmd==) an alternate boot action will be performed, and the contents of ==altbootcmd== will be executed. If the variable ==bootlimit== is not defined in the environment, the Boot Count Limit feature is disabled. If it is enabled, but ==altbootcmd== is not defined, then U-Boot will drop into interactive mode and remain there. It is the responsibility of some application code (typically a Linux application) to reset the variable ==bootcount==, thus allowing for more boot cycles. %X% At the moment, the Boot Count Limit feature is available only for MPC8xx, MPC82xx and MPC5200 [[PowerPC][Power Architecture]]® processors. * [[%ATTACHURL%/ubootBootcountAccess.c][ubootBootcountAccess.c]]: C-source: bootcount access through /proc file system
5.14. U-Boot Advanced Features
1. Abstract
6. Embedded Linux Configuration
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