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Diffstat (limited to 'README')
| -rw-r--r-- | README | 70 |
1 files changed, 0 insertions, 70 deletions
@@ -3412,76 +3412,6 @@ following configurations: Builds up envcrc with the target environment so that external utils may easily extract it and embed it in final U-Boot images. -- CONFIG_ENV_IS_IN_FLASH: - - Define this if the environment is in flash memory. - - a) The environment occupies one whole flash sector, which is - "embedded" in the text segment with the U-Boot code. This - happens usually with "bottom boot sector" or "top boot - sector" type flash chips, which have several smaller - sectors at the start or the end. For instance, such a - layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In - such a case you would place the environment in one of the - 4 kB sectors - with U-Boot code before and after it. With - "top boot sector" type flash chips, you would put the - environment in one of the last sectors, leaving a gap - between U-Boot and the environment. - - - CONFIG_ENV_OFFSET: - - Offset of environment data (variable area) to the - beginning of flash memory; for instance, with bottom boot - type flash chips the second sector can be used: the offset - for this sector is given here. - - CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE. - - - CONFIG_ENV_ADDR: - - This is just another way to specify the start address of - the flash sector containing the environment (instead of - CONFIG_ENV_OFFSET). - - - CONFIG_ENV_SECT_SIZE: - - Size of the sector containing the environment. - - - b) Sometimes flash chips have few, equal sized, BIG sectors. - In such a case you don't want to spend a whole sector for - the environment. - - - CONFIG_ENV_SIZE: - - If you use this in combination with CONFIG_ENV_IS_IN_FLASH - and CONFIG_ENV_SECT_SIZE, you can specify to use only a part - of this flash sector for the environment. This saves - memory for the RAM copy of the environment. - - It may also save flash memory if you decide to use this - when your environment is "embedded" within U-Boot code, - since then the remainder of the flash sector could be used - for U-Boot code. It should be pointed out that this is - STRONGLY DISCOURAGED from a robustness point of view: - updating the environment in flash makes it always - necessary to erase the WHOLE sector. If something goes - wrong before the contents has been restored from a copy in - RAM, your target system will be dead. - - - CONFIG_ENV_ADDR_REDUND - CONFIG_ENV_SIZE_REDUND - - These settings describe a second storage area used to hold - a redundant copy of the environment data, so that there is - a valid backup copy in case there is a power failure during - a "saveenv" operation. - -BE CAREFUL! Any changes to the flash layout, and some changes to the -source code will make it necessary to adapt <board>/u-boot.lds* -accordingly! - - - CONFIG_ENV_IS_IN_NVRAM: Define this if you have some non-volatile memory device |