[U-Boot-Custodians] SPL / TPL

Wolfgang Denk wd at denx.de
Thu Oct 10 06:52:08 UTC 2019

Dear Joe,

In message <CANr=Z=bmYr7SR8kuDDjuUGxMijqVa1SU6y=acuxttkq-6DoSoA at mail.gmail.com> you wrote:
> I agree that this term should not be hijacked. I think that what is
> likely is that they needed a new thing even smaller than SPL and
> didn't need a thing bigger than SPL that wasn't already just U-Boot,

Sorry, but I cannot understand this argument.  You sound as if there
was something that dictates a minimum size for the SPL.  There are
many systems with tight restrictions - say some Atmel AT91 like the
one in board/siemens/smartweb where the SPL has to fit in a 4 kB

> and just hijaked the configuration that existed since it (TPL) is far
> less mature and used in far fewer scenarios. I think they should have
> made a different config and different name for their case... Early
> Program Loader? I don't know.

I don't understand why that would be needed.  If the SPL can be as
small as in the smartweb case there should be no need to come up
with something new.

> The one thing that I'm glad they didn't do is re-implement all of SPL
> as TPL just because they need an additional binary. I suspect there is
> a fair amount of refactoring needed if that is the goal you are hoping
> for.

If the goal is just to have a really small initial stage and a
somewhat bigger intermediate stage before they can load U-Boot
proper, then the existing organization should just work fine.  The
small initial stage is the SPL, of course.  See smartweb as a
working example.

Yes, this probably means that for those system(s) which got it wron
code may have to be moved from TPL into SPL and vice versa, to get
things right.  But that should have been done right from the
beginning; I consider this a bug fix.

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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