Convert CONFIG_ENV_IS_IN_FLASH to Kconfig

[u-boot.git] / common / Kconfig

diff --git a/common/Kconfig b/common/Kconfig
index de7584f7783bc0865dc73c4420b5e0955974da3b..29e25fef2f5ba392728dcbca1080f2538ea0d1b2 100644 (file)
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -176,6 +176,78 @@ endmenu
 
 menu "Environment"
 
+config ENV_IS_IN_FLASH
+       bool "Environment in flash memory"
+       depends on !CHAIN_OF_TRUST
+       help
+         Define this if you have a flash device which you want to use for the
+         environment.
+
+         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_MMC
        bool "Environment in an MMC device"
        depends on !CHAIN_OF_TRUST