[U-Boot] [PATCH 10/10] ARM: socfpga: arria10: add support for building Arria10

[Marek Vasut]

On Tuesday, November 24, 2015 at 02:36:13 PM, Chin Liang See wrote:
> Hi Pavel,
> 
> On Tue, 2015-11-24 at 14:31 +0100, Pavel Machek wrote:
> > Hi!
> > 
> > > > > > So what do I do if I want to boot arria10 from NAND ? UBI and
> > > > > > UBIFS
> > > > > > won't
> > > > > > fit into 256kiB, so I think using SPL might be the sensible
> > > > > > thing
> > > > > > afterall,
> > > > > > since you would be able to use arbitrarily-sized U-Boot.
> > > > > 
> > > > > I hope Chin Liang can chime here, I know that we have support
> > > > > for
> > > > > NAND,
> > > > > but I haven't been part of that task, so I don't know how it's
> > > > > being
> > > > > done.
> > > > 
> > > > Finally my email is back online :)
> > > > 
> > > > We do have NAND support but not with UBI and UBIFS.
> > > 
> > > I just hope you're not using raw NAND and just hoping it will work.
> > 
> > HERE:
> > > > For this support, user can use U-Boot to load arbitrarily-sized U
> > > > -Boot
> > > > that run on SDRAM.
> > 
> > ...
> > 
> > > > One of the nice thing of U-Boot over SPL is the console support
> > > > and
> > > > ability to troubleshoot.
> > > > This is possible with Arria 10 SoC as we have larger OCRAM (256kB
> > > > vs CV
> > > > SoC 64kB).
> > > 
> > > OK, that's not really the point here -- the point is, if you
> > > compile enough
> > > features into U-Boot, it will be bigger than those 256k. What will
> > > you do
> > > then ?
> > 
> > You'll compile small U-Boot, and use it to load larger U-Boot, as he
> > said in the mark "HERE" above.
> > 
> > And yes, I guess that makes sense, and yes, we should finally make
> > loading U-Boot from U-Boot oficially supported, at least on Socfpga.
> 
> Yup, you got it :)
> Thanks

So why exactly don't we use SPL instead ? The purpose of SPL is to do exactly 
this without the extra cruft which is part of U-Boot and the unnecessary 
overhead of the full U-Boot. And you don't need to hack U-Boot to support 
loading U-Boot.

Best regards,
Marek Vasut