[PATCH] Makefile: add target to produce a SPL compatible uImage

[Jan Lübbe]

On Tue, 2012-09-25 at 14:29 +0200, Teresa Gamez wrote:
> Am 24.09.2012 14:49, schrieb Jan Lübbe:
> > On Mon, 2012-09-24 at 14:37 +0200, Teresa Gamez wrote:
> >> I have tested it with my am335x patches. And it worked so far.
> >> But I have not done anything with the pbl image, yet.
> >> Could you explain me what it's actually for? And how I can test it?
> > Thanks!
> >
> > PBL stands for Pre-Bootloader Image, which is used to have a compressed
> > barebox binary. You can enable it in "General Settings -> memory layout
> > -> Pre-Bootloader image".
> 
> Do I understand this correctly that this is suppose to be used to decrease
> the size of first stage bootloader binaries like the MLO on ti boards?

I don't think it is useful in the current form for the MLO case. The
problem there is that the SRAM would be too small to contain the
decompressed image (in addition to the compressed one). 

It saves some time when loading from slower flash and is useful when the
space for barebox in flash is limited some how (but you have enough
RAM).

For the MLO case we would need to have the DRAM setup in the
Pre-Bootloader and then decompress to DRAM. That should be possible, but
I'm not sure how much we'd gain (the compressed image would still be
limited by SRAM size).

Regards,
Jan
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