xref: /openbmc/u-boot/tools/env/README (revision 8e6f1a8e)
1
2This is a demo implementation of a Linux command line tool to access
3the U-Boot's environment variables.
4
5For the run-time utiltity configuration uncomment the line
6#define CONFIG_FILE  "/etc/fw_env.config"
7in fw_env.h.
8
9See comments in the fw_env.config file for definitions for the
10particular board.
11
12Configuration can also be done via #defines in the fw_env.h file. The
13following lines are relevant:
14
15#define HAVE_REDUND	/* For systems with 2 env sectors */
16#define DEVICE1_NAME	"/dev/mtd1"
17#define DEVICE2_NAME	"/dev/mtd2"
18#define DEVICE1_OFFSET    0x0000
19#define ENV1_SIZE         0x4000
20#define DEVICE1_ESIZE     0x4000
21#define DEVICE2_OFFSET    0x0000
22#define ENV2_SIZE         0x4000
23#define DEVICE2_ESIZE     0x4000
24
25Current configuration matches the environment layout of the TRAB
26board.
27
28Un-define HAVE_REDUND, if you want to use the utlities on a system
29that does not have support for redundant environment enabled.
30If HAVE_REDUND is undefined, DEVICE2_NAME is ignored,
31as is ENV2_SIZE and DEVICE2_ESIZE.
32
33The DEVICEx_NAME constants define which MTD character devices are to
34be used to access the environment.
35
36The DEVICEx_OFFSET constants define the environment offset within the
37MTD character device.
38
39ENVx_SIZE defines the size in bytes taken by the environment, which
40may be less then flash sector size, if the environment takes less
41then 1 sector.
42
43DEVICEx_ESIZE defines the size of the first sector in the flash
44partition where the environment resides.
45