[U-Boot] Making U-Boot smaller

[Marek Vasut]

On 5/21/19 6:56 PM, Jagan Teki wrote:
> On Tue, May 21, 2019 at 10:14 PM Simon Glass <sjg at chromium.org> wrote:
>>
>> Hi,
>>
>> (moved from thread "U-Boot PXA support")
>>
>> We have of-platdata, which produces C data from the DT, for linking
>> into U-Boot. It saves libfdt and DT space. But we still have the DM
>> overhead.
>>
>> We have binman which can insert values into the binary after
>> link-time. This is barely used at present, only for accessing the
>> location of things in flash.
>>
>> Another thing is that every little tweak and feature adds a few bytes
>> and there are dozens of them in each release. It would be interesting
>> to build a board from 10 years ago (like PXA) and see where the growth
>> is. My bet is that we could add Kconfig options to disable extra
>> features (and enhancements of features) and make quite a difference.
>>
>> For DM, I think it would be interesting to revisit and compare against
>> the initial release, and see if some features could be made optional
>> in SPL.
>>
>> Finally I feel we could implement a single-device API for where
>> CONFIG_SPL_DM is not set. We could use the debug UART for serial, a
>> single instance of tiny MMC for MMC, etc.
> 
> This is what I'm looking for quite sometime, a tiny MMC which would
> bypass the mmc stack and do the possible stuff in SPL, since we don't
> have any option to use full DM in SPL (specifically for Allwinner 64
> SoC's). API that would atleast compatible with DM with small
> foot-print would help.

It's been in mainline for a long time, MMC_TINY. Creator CI20 uses it.

-- 
Best regards,
Marek Vasut