[U-Boot] SPL framework re-design

[Aneesh V]

Hi Daniel,

This looks like an interesting alternative.

On Thursday 16 June 2011 06:25 PM, Daniel Schwierzeck wrote:
> Hi all,
>
> for my MIPS based boards I tested a approach similar to Wolfgang's one
> in the last weeks.
> My goal was to create a SPL image, that is able to boot from a SPI flash.
>
> The basic idea is to have a spl directory that is used as remote build
> directory for all object files
> needed for the SPL image. It contains only the Makefile and nothing
> else. This Makefile is
> a strongly simplified version of the TOPDIR/Makefile, uses
> TOPDIR/config.mk and creates
> a u-boot-spl.bin. The SPL build can be enabled by defining
> CONFIG_UBOOT_SPL in the board config file.

In the last few mails Wolfgang was suggesting re-use of object files
themselves, not the source files. In this respect his approach may be
different from yours. But I think his objective was to avoid the
symbolic link business, which this approach achieves.

>
> If the spl/Makefiles becomes active, an additional variable name
> CONFIG_UBOOT_SPL_BUILD wiil be
> exported in the make environment. Additionally
> -DCONFIG_UBOOT_SPL_BUILD will be added
> to the CFLAGS (similar to -DCONFIG_PRELOADER). This allows us to reuse
> almost of the arch, SoC and
> board code.

So, you are essentially re-using the make infrastructure of normal
U-Boot with a different top-level Makefile and the additional flags,
right?

With this scheme can you build two different SPLs for a given board,
let's say a NAND spl and another MMC spl. I don't know if this is a
valid case, but just wondering. I guess you have a unique u-boot-
spl.bin much like you have single u-boot.bin, right?

Will you be sending your patches to the list?

best regards,
Aneesh