[U-Boot] [U-Boot, v3, 02/15] kbuild: add a makefile macro useful with per-image config options

Tom Rini
2015-08-18T17:52:36Z

On Wed, Aug 12, 2015 at 07:31:42AM +0900, Masahiro Yamada wrote:

> Commit e02ee2548afe ("kconfig: switch to single .config
> configuration") made the configuration itself pretty simple,
> instead, we lost the way to systematically enable/disable config
> options for each image independently.
>
> Our current strategy is, put entries into Makefile.spl for options
> we need separate enabling, or once enable the options globally in
> Kconfig and then undef them in Makefile.uncmd_spl if we do not want
> to compile the features for SPL at all. Things are getting really
> messy. Besides, "ifdef CONFIG_SPL_BUILD" are sprinkled everywhere
> in makefiles.
>
> This commit adds a variable to help describe makefile simpler.
>
> $(SPL_) evaluates to "SPL_" during the SPL build, while to an empty
> string during building U-boot proper.
>
> So, you can write
>
> obj-$(CONFIG_$(SPL_)FOO) += foo.o
>
> instead of
>
> ifdef CONFIG_SPL_BUILD
> obj-$(CONFIG_SPL_FOO) += foo.o
> else
> obj-$(CONFIG_FOO) += foo.o
> endif
>
> If CONFIG_SPL_FOO does not exist in Kconfig, it is equivalent to
>
> ifndef CONFIG_SPL_BUILD
> obj-$(CONFIG_SPL_FOO) += foo.o
> endif
>
> This is the pattern we often see in our current makefiles.
>
> To take advantage of this macro, we should prefix SPL_ for the SPL
> version of the option when we need independent control between
> U-boot and SPL. With this naming scheme, I hope our makefiles will
> be much simplified.
>
> It means we want to rename existing config options as follows
> in the long run:
>
> CONFIG_SPL_SERIAL_SUPPORT -> CONFIG_SPL_SERIAL
> CONFIG_SPL_I2C_SUPPORT -> CONFIG_SPL_I2C
> CONFIG_SPL_GPIO_SUPPORT -> CONFIG_SPL_GPIO
> CONFIG_SPL_SPI_SUPPORT -> CONFIG_SPL_SPI
> CONFIG_SPL_DISABLE_OF_CONTROL -> CONFIG_SPL_OF_CONTROL
> (inverting the logic)
>
> Then drivers/Makefile would be re-worked as follows:
>
> obj-$(CONFIG_$(SPL_)SERIAL) += serial/
> obj-$(CONFIG_$(SPL_)I2C) += i2c/
> obj-$(CONFIG_$(SPL_)GPIO) += gpio/
> obj-$(CONFIG_$(SPL_)SPI) += spi/
> ...
>
> Eventually, SPL-specialized entries in Makefile.spl would go away.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> Reviewed-by: Tom Rini <trini@konsulko.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

--
Tom
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