- This target updates .config, include/generated/autoconf.h and
- include/configs/*. In U-Boot, the same thing is done for SPL, TPL,
- if supported by the target board. Depending on whether CONFIG_SPL and
- CONFIG_TPL are defined, "make silentoldconfig" iterates three times at most
- changing the work directory.
-
- To sum up, "make silentoldconfig" possibly updates:
- - .config, include/generated/autoconf.h, include/config/*
- - spl/.config, spl/include/generated/autoconf.h, spl/include/config/*
- (in case CONFIG_SPL=y)
- - tpl/.config, tpl/include/generated/autoconf.h, tpl/include/config/*
- (in case CONFIG_TPL=y)
-
-- defconfig, <board>_defconfig
-
- The target "<board>_defconfig" is used to create the .config based on the
- file configs/<board>_defconfig. The "defconfig" target is the same
- except it checks for a file specified with KBUILD_DEFCONFIG environment.
-
- Note:
- The defconfig files are placed under the "configs" directory,
- not "arch/$(ARCH)/configs". This is because "ARCH" is not necessarily
- given from the command line for the U-Boot configuration and build.
-
- The defconfig file format in U-Boot has the special syntax; each line has
- "<condition>:" prefix to show which image(s) the line is valid for.
- For example,
-
- CONFIG_FOO=100
- S:CONFIG_FOO=200
- T:CONFIG_FOO=300
- ST:CONFIG_BAR=y
- +S:CONFIG_BAZ=y
- +T:CONFIG_QUX=y
- +ST:CONFIG_QUUX=y
-
- Here, the "<condition>:" prefix is one of:
- None - the line is valid only for Normal image
- S: - the line is valid only for SPL image
- T: - the line is valid only for TPL image
- ST: - the line is valid for SPL and TPL images
- +S: - the line is valid for Normal and SPL images
- +T: - the line is valid for Normal and TPL images
- +ST: - the line is valid for Normal, SPL and SPL images
-
- So, if neither CONFIG_SPL nor CONFIG_TPL is defined, the defconfig file
- has no "<condition>:" part and therefore has the same form as in Linux.
- From the example defconfig shown above, three separete configuration sets
- are generated and used for creating .config, spl/.config and tpl/.config.
-
- - Input for the default configuration of Normal
- CONFIG_FOO=100
- CONFIG_BAZ=y
- CONFIG_QUX=y
- CONFIG_QUUX=y
-
- - Input for the default configuration of SPL
- CONFIG_FOO=200
- CONFIG_BAR=y
- CONFIG_BAZ=y
- CONFIG_QUUX=y
-
- - Input for the default configuration of TPL
- CONFIG_FOO=300
- CONFIG_BAR=y
- CONFIG_QUX=y
- CONFIG_QUUX=y
-
-- savedefconfig
-
- This is the reverse operation of "make defconfig". If neither CONFIG_SPL
- nor CONFIG_TPL is defined in the .config file, it works like "savedefconfig"
- in Linux Kernel: creates the minimal set of config based on the .config
- and saves it into the "defconfig" file. If CONFIG_SPL (and CONFIG_TPL) is
- defined, the common lines among .config, spl/.config (and tpl/.config) are
- coalesced together with "<condition:>" prefix for each line as shown above.
- This file can be used as an input of "defconfig" target.