[U-Boot] Difference between _defconfig and _config make switches

[Chris Packham]

On Tue, Jun 25, 2019 at 9:49 AM Robert P. J. Day <rpjday at crashcourse.ca> wrote:
>
> On Tue, 25 Jun 2019, Ahmad Ijaz wrote:
>
> > Hi Sir,
> >
> > I am trying to understand u-boot source code. As a starting point, I
> > compiled u-boot for beaglebone black and successfully executed it on
> > beaglebone hardware.
> > My question is related to compilation step.
> >
> > The u-boot can be compiled with the following switches on *make.*
> >
> > *1. am335x_beaglebone_defconfig*
> > *2. am335x_beaglebone_config*
> > *3. am335x_evm_defconfig*
> > *4. am335x_evm_config*
>
>   from scripts/kconfig/Makefile:
>
> # Added for U-Boot (backward compatibility)
> %_config: %_defconfig
>         @:

Historically _config was used. When u-boot started using Kbuild the
defconfig files were created and the Makefile rule that Robert pointed
out was added for compatibility with any external scripting that
people might have.