[U-Boot] [RFC PATCH 1/2] kbuild: add a makefile macro useful with per-image config options

[Tom Rini]

On Tue, Jul 28, 2015 at 12:19:07AM +0900, Masahiro Yamada wrote:
> Tom,
> 
> 
> 2015-07-28 0:08 GMT+09:00 Tom Rini <trini at konsulko.com>:
> > On Thu, Jul 23, 2015 at 08:31:55PM +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 macro to help describe makefile simpler, allowing
> >> separate switch for U-boot main and SPL.
> >>
> >> This macro takes a config option without the prefix CONFIG_.
> >> $(call CONFIG,FOO) evaluates to
> >>   $(CONFIG_FOO) if CONFIG_SPL_BUILD is undefined (U-boot build),
> >>   $(CONFIG_SPL_FOO) if CONFIG_SPL_BUILD is defined (SPL_BUILD).
> >>
> >> That is,
> >>
> >>   $(call CONFIG,FOO) += foo.o
> >>
> >> is a shorthand for
> >>
> >>   ifdef CONFIG_SPL_BUILD
> >>   obj-$(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 that we need independent control between
> >> U-boot and SPL.  With this naming scheme, we only have to add a
> >> single line in a Makefile for each config option.
> >>
> >> 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-$(call CONFIG,SERIAL)  += serial/
> >>   obj-$(call CONFIG,I2C)     += i2c/
> >>   obj-$(call CONFIG,GPIO)    += gpio/
> >>   obj-$(call CONFIG,SPI)     += spi/
> >>      ...
> >>
> >> Eventually, SPL-specialized entries in Makefile.spl would go away.
> >>
> >> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
> >
> > Reviewed-by: Tom Rini <trini at konsulko.com>
> >
> 
> This patch was superseded by
> 
> http://patchwork.ozlabs.org/patch/500034/
> 
> 
> If you do not mind, I will put your Reviewed-by there
> when I send the next version.

I kinda thought that's how it was looking in my inbox.  I'll read that
whole series later today.

-- 
Tom
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