xref: /openbmc/u-boot/tools/env/README (revision d0fb80c3021e15853895e9ae45ab9368d0fb52fa)
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26aff3115SwdenkThis is a demo implementation of a Linux command line tool to access
36aff3115Swdenkthe U-Boot's environment variables.
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5*d0fb80c3SwdenkFor the run-time utiltity configuration uncomment the line
6*d0fb80c3Swdenk#define CONFIG_FILE  "/etc/fw_env.config"
7*d0fb80c3Swdenkin fw_env.h.
8*d0fb80c3Swdenk
9*d0fb80c3SwdenkSee comments in the fw_env.config file for definitions for the
10*d0fb80c3Swdenkparticular board.
11*d0fb80c3Swdenk
12*d0fb80c3SwdenkConfiguration can also be done via #defines in the fw_env.h file. The
136aff3115Swdenkfollowing lines are relevant:
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156aff3115Swdenk#define HAVE_REDUND	/* For systems with 2 env sectors */
166aff3115Swdenk#define DEVICE1_NAME	"/dev/mtd1"
176aff3115Swdenk#define DEVICE2_NAME	"/dev/mtd2"
18*d0fb80c3Swdenk#define DEVICE1_OFFSET    0x0000
196aff3115Swdenk#define ENV1_SIZE         0x4000
206aff3115Swdenk#define DEVICE1_ESIZE     0x4000
21*d0fb80c3Swdenk#define DEVICE2_OFFSET    0x0000
226aff3115Swdenk#define ENV2_SIZE         0x4000
236aff3115Swdenk#define DEVICE2_ESIZE     0x4000
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256aff3115SwdenkCurrent configuration matches the environment layout of the TRAB
266aff3115Swdenkboard.
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286aff3115SwdenkUn-define HAVE_REDUND, if you want to use the utlities on a system
29*d0fb80c3Swdenkthat does not have support for redundant environment enabled.
30*d0fb80c3SwdenkIf HAVE_REDUND is undefined, DEVICE2_NAME is ignored,
31*d0fb80c3Swdenkas is ENV2_SIZE and DEVICE2_ESIZE.
32*d0fb80c3Swdenk
33*d0fb80c3SwdenkThe DEVICEx_NAME constants define which MTD character devices are to
34*d0fb80c3Swdenkbe used to access the environment.
35*d0fb80c3Swdenk
36*d0fb80c3SwdenkThe DEVICEx_OFFSET constants define the environment offset within the
37*d0fb80c3SwdenkMTD character device.
38*d0fb80c3Swdenk
39*d0fb80c3SwdenkENVx_SIZE defines the size in bytes taken by the environment, which
40*d0fb80c3Swdenkmay be less then flash sector size, if the environment takes less
41*d0fb80c3Swdenkthen 1 sector.
42*d0fb80c3Swdenk
436aff3115SwdenkDEVICEx_ESIZE defines the size of the first sector in the flash
44*d0fb80c3Swdenkpartition where the environment resides.
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