[U-Boot] What is the correct way to configure SPL options?

[Tom Rini]

On Thu, May 17, 2012 at 12:13:20PM +1200, Charles Manning wrote:
> Hi All
> 
> My understanding of the way SPL is intended to be configured is:
> 
> (a) You have one config file for both SPL and u-boot.

Yes.

> (b) SPL features are selected via SPL-specific options.

For some parts, yes.  Note that SPL does use
-ffunction-sections/-fdata-sections/--gc-sections.

> I have a need to build SPL with MMC/FAT support, but I don't want
> u-boot to have MMC/FAT support.

This is a new challenge, yes.

> I do however see that quite a few SPL feature selections don't use SPL
> config definitions though which would seem to violate (b) above.
> 
> eg.drivers/mmc/Makefile contains
> COBJS-$(CONFIG_GENERIC_MMC) += mmc.o
> 
> It seems to me there are three ways to address this:
> 
> A) Change all those Makefiles to something like:
> 
> ifdef CONFIG_SPL_BUILD
> COBJS-$(CONFIG_SPL_MMC_SUPPORT) += mmc.o
> else
> COBJS-$(CONFIG_GENERIC_MMC) += mmc.o
> endif
> 
> 
> B) Modifying the config file with something like
> 
> #ifdef CONFIG_SPL_BUILD
> #define CONFIG_GENERIC_MMC
> ...
> #endif
> 
> C) Separate config files. One for SPL and the other for u-boot.
> 
> Which is the best way to do this?

I think (B) is the method to go with.  We already do this with certain
things like CONFIG_SKIP_LOW_LEVEL_INIT.

-- 
Tom