[PATCH 1/1] doc: describe TPL/VPL/SPL boot

[Tom Rini]

On Wed, Aug 23, 2023 at 10:14:00PM +0200, Pali Rohár wrote:
> On Wednesday 23 August 2023 21:57:28 Heinrich Schuchardt wrote:
> > +Booting from TPL/SPL
> > +====================
> > +
> > +The main U-Boot binary may be to large to be loaded directly by the Boot ROM.
> > +This was the main driver for splitting up U-Boot into multiple boot stages with
> > +successively larger binaries.
> > +
> > +U-Boot typically goes through the following boot phases where TPL, VPL, and SPL
> > +are optional. While many boards use SPL only few use TPL.
> > +
> > +TPL
> > +   Very early init, as tiny as possible. This loads SPL (or VPL if enabled).
> 
> This is not truth. SPL loads TPL. Or at least it was about year ago for powerpc plat.
> 
> > +VPL
> > +   Optional verification step, which can select one of several SPL binaries,
> > +   if A/B verified boot is enabled. Implementation of the VPL logic is
> > +   work-in-progress. For now it just boots into SPL.
> > +
> > +SPL
> > +   Secondary program loader. Sets up SDRAM and loads U-Boot proper. It may also
> > +   load other firmware components.
> 
> SPL initializes NAND then loads TPL from NAND, TPL initialize DDR and then loads U-Boot.

One of the long standing issues here is that PowerPC is different from
everyone else, in terms of terminology here.

-- 
Tom
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 659 bytes
Desc: not available
URL: <https://lists.denx.de/pipermail/u-boot/attachments/20230823/0c01303a/attachment.sig>