Re: [PATCH v4 0/5] Add fastboot to SPL

[Stefan Monnier <monnier@iro.umontreal.ca>]

Carlo Caione [2026-08-21 09:05:37] wrote:
> It is possible to include U-Boot proper in the host-loaded bootstrap
> and use its existing fastboot implementation. That is a valid approach
> and is preferable where the Boot ROM download limit and memory budget
> allow it.

Right, that's the situation I'm familiar with.

> But it is not always possible: some platforms (like the one we are
> enabling) impose a strict size limit on the bootstrap, or only provide
> enough early memory for the DDR initialization code and (small)
> SPL-sized payload.

I associate "fastboot" with the Android nebula, so I find it hard to
imagine a machine with enough resources to run Android yet with a small
enough boot memory for U-Boot not to fit into it.  I assume the SPL is
pre-installed in some dedicated boot memory (SPI NOR?) whereas the main
storage is left uninitialized during production.  And the NOR flash is
so small that it can't even accommodate a proper U-Boot?

I wonder how many cents it saves the manufacturer (e.g. compared to
having a slightly bigger NOR, or not having the NOR at all and
pre-installing U-Boot on the main storage) 🙁

Anyway, this is clearly getting offtopic.  Thanks for the answer.


=== Stefan