[U-Boot] [RFC PATCH 4/6] porter_defconfig: Enable tiny printf

[Miquel Raynal]

Hi Vignesh,

> >> While I think porting this from Linux is the right thing to do, I can't
> >> say I'm happy with losing yet another 2.5 kB for SPL when it is already
> >> too stuffed to add secure boot via FIT signatures.  
> > 
> > Indeed. Can we somehow trim things down a bit for SPL ?
> >   
> 
> I am able to trim overall size delta to within 1KB for porter_defconfig.
> Pushed new set of patches to github[1]
> 
> With new this new SF framework and porter_defconfig:
> size spl/u-boot-spl
>    text	   data	    bss	    dec	    hex	filename
>   15749	    184	   1100	  17033	   4289	spl/u-boot-spl
> 
> Current mainline:
> size spl/u-boot-spl
>    text	   data	    bss	    dec	    hex	filename
>   14881	    184	   1100	  16165	   3f25	spl/u-boot-spl
> 
> Typical increase in code delta is ~1K to ~1.2KB wrt SPL on different
> platforms depending on flash devices supports enabled.
> 
> I am not sure if its possible to trim this down further, as there is
> addition of new code to handle 4 Byte addressing feature and moving to
> spi-mem framework to support direct mapping capable SPI controllers.
> These features will add to code size and I hope that's an acceptable
> tradeoff.
> 
> I believe, once SPI NOR is completely integrated with MTD framework,
> there will be some size reduction(such as due to getting rid of sf_mtd.c
> and spi_flash_* APIs completely. Also, loading of U-Boot images across
> NAND/SPI NOR can be consolidated).

There are already multiple SPL-specific drivers out there. While I don't
see a problem building MTD in U-Boot, I wonder if building MTD in the
SPL is a good idea. Instead, Why not just build a tiny "SPL MTD stack",
a lightweight MTD stack just with minimal features?

> 
> I will post revised patches to mailing list after travis ci report.
> 
> [1] https://github.com/r-vignesh/u-boot.git spi-nor-mig-v2
> 


Thanks,
Miquèl