[U-Boot] Building two different "SPL" for the same board?

[Tom Rini]

On Fri, May 17, 2013 at 08:06:07PM +0200, Henrik Nordstr?m wrote:

> I am looking into reusing the SPL system initialization part for a very
> minimalistic "SPL" which only initializes the board.
> 
> To give a bit of context, on the Allwinner CPUs there is a recovery boot
> mode where data can be copied over USB and executed by the CPU. But most
> of the board including DRAM controller is not initialized by default so
> the very first thing you need to do is to upload & execute board
> initialization code (but excluding CPU initialization).
> 
> Note: It is not really an SPL as all it does is initializing the board
> and then returning control to the USB loader so additional code
> (u-boot.bin) can be uploaded to DRAM and executed.
> 
> I have this implemented today partially out-of-tree leaching objects
> from an u-boot build to build a binary with the initialization code. My
> question is if it would make sense to try integrate this into the u-boot
> tree somehow. Have something similar been done for any other board?
> 
> The current "code" is at
> https://github.com/linux-sunxi/sunxi-tools/tree/master/felboot
> mainly main.c (entry + stubs), the rest is only for a small printf and
> is not needed.

I would say you want to hypothetically add a _felboot build target for
the allwinner boards that instead of building out a regular
CONFIG_SPL_FRAMEWORK (I hope!) SPL spits out just a very tiny one that
does what you need for this use case.  Having different builds for
different SPL cases is a normal thing that we do on a few boards, but
none are quite so drastically different sounding as this.

-- 
Tom
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