README 2.3 KB

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  1. This is a demo implementation of a Linux command line tool to access
  2. the U-Boot's environment variables.
  3. In order to cross-compile fw_printenv, run
  4. make CROSS_COMPILE=<your cross-compiler prefix> envtools
  5. in the root directory of the U-Boot distribution. For example,
  6. make CROSS_COMPILE=arm-linux- envtools
  7. You should then create a symlink from fw_setenv to fw_printenv. They use
  8. the same program and its function depends on its basename.
  9. For the run-time utility configuration uncomment the line
  10. #define CONFIG_FILE "/etc/fw_env.config"
  11. in fw_env.h.
  12. For building against older versions of the MTD headers (meaning before
  13. v2.6.8-rc1) it is required to pass the argument "MTD_VERSION=old" to
  14. make.
  15. See comments in the fw_env.config file for definitions for the
  16. particular board.
  17. Configuration can also be done via #defines in the fw_env.h file. The
  18. following lines are relevant:
  19. #define HAVE_REDUND /* For systems with 2 env sectors */
  20. #define DEVICE1_NAME "/dev/mtd1"
  21. #define DEVICE2_NAME "/dev/mtd2"
  22. #define DEVICE1_OFFSET 0x0000
  23. #define ENV1_SIZE 0x4000
  24. #define DEVICE1_ESIZE 0x4000
  25. #define DEVICE1_ENVSECTORS 2
  26. #define DEVICE2_OFFSET 0x0000
  27. #define ENV2_SIZE 0x4000
  28. #define DEVICE2_ESIZE 0x4000
  29. #define DEVICE2_ENVSECTORS 2
  30. Un-define HAVE_REDUND, if you want to use the utilities on a system
  31. that does not have support for redundant environment enabled.
  32. If HAVE_REDUND is undefined, DEVICE2_NAME is ignored,
  33. as is ENV2_SIZE and DEVICE2_ESIZE.
  34. The DEVICEx_NAME constants define which MTD character devices are to
  35. be used to access the environment.
  36. The DEVICEx_OFFSET constants define the environment offset within the
  37. MTD character device.
  38. ENVx_SIZE defines the size in bytes taken by the environment, which
  39. may be less then flash sector size, if the environment takes less
  40. then 1 sector.
  41. DEVICEx_ESIZE defines the size of the first sector in the flash
  42. partition where the environment resides.
  43. DEVICEx_ENVSECTORS defines the number of sectors that may be used for
  44. this environment instance. On NAND this is used to limit the range
  45. within which bad blocks are skipped, on NOR it is not used.
  46. To prevent losing changes to the environment and to prevent confusing the MTD
  47. drivers, a lock file at /var/lock/fw_printenv.lock is used to serialize access
  48. to the environment.