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- This is a demo implementation of a Linux command line tool to access
- the U-Boot's environment variables.
- In order to cross-compile fw_printenv, run
- make CROSS_COMPILE=<your cross-compiler prefix> env
- in the root directory of the U-Boot distribution. For example,
- make CROSS_COMPILE=arm-linux- env
- For the run-time utility configuration uncomment the line
- #define CONFIG_FILE "/etc/fw_env.config"
- in fw_env.h.
- For building against older versions of the MTD headers (meaning before
- v2.6.8-rc1) it is required to pass the argument "MTD_VERSION=old" to
- make.
- See comments in the fw_env.config file for definitions for the
- particular board.
- Configuration can also be done via #defines in the fw_env.h file. The
- following lines are relevant:
- #define HAVE_REDUND /* For systems with 2 env sectors */
- #define DEVICE1_NAME "/dev/mtd1"
- #define DEVICE2_NAME "/dev/mtd2"
- #define DEVICE1_OFFSET 0x0000
- #define ENV1_SIZE 0x4000
- #define DEVICE1_ESIZE 0x4000
- #define DEVICE1_ENVSECTORS 2
- #define DEVICE2_OFFSET 0x0000
- #define ENV2_SIZE 0x4000
- #define DEVICE2_ESIZE 0x4000
- #define DEVICE2_ENVSECTORS 2
- Un-define HAVE_REDUND, if you want to use the utilities on a system
- that does not have support for redundant environment enabled.
- If HAVE_REDUND is undefined, DEVICE2_NAME is ignored,
- as is ENV2_SIZE and DEVICE2_ESIZE.
- The DEVICEx_NAME constants define which MTD character devices are to
- be used to access the environment.
- The DEVICEx_OFFSET constants define the environment offset within the
- MTD character device.
- ENVx_SIZE defines the size in bytes taken by the environment, which
- may be less then flash sector size, if the environment takes less
- then 1 sector.
- DEVICEx_ESIZE defines the size of the first sector in the flash
- partition where the environment resides.
- DEVICEx_ENVSECTORS defines the number of sectors that may be used for
- this environment instance. On NAND this is used to limit the range
- within which bad blocks are skipped, on NOR it is not used.
- To prevent losing changes to the environment and to prevent confusing the MTD
- drivers, a lock file at /var/lock/fw_printenv.lock is used to serialize access
- to the environment.
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