[U-Boot-Custodians] SPL / TPL

[Bin Meng]

Hi Kever,

On Wed, Oct 9, 2019 at 9:58 AM Kever Yang <kever.yang at rock-chips.com> wrote:
>
>
> On 2019/10/8 下午11:31, Bin Meng wrote:
> > Hi,
> >
> > Simon is on vacation, hence I hoped to get the clarification from
> > other maintainers.
> >
> > As I see in U-Boot currently only NXP PowerPC uses TPL in the NAND
> > configurations, and some ARM boards use TPL.
> >
> > It looks in x86 we are using TPL in a different boot flow and this
> > confused me a lot in the past.
> > In x86 we expect TPL to load SPL then U-Boot proper. (TPL => SPL =>
> > U-Boot proper)
> >
> > However in README.TPL, it says TPL is the 3rd program loader, to be
> > loaded by SPL. So if my read is correct, the expected boot flow is SPL
> > => TPL => U-Boot proper.
> >
> > I believe only one boot flow is the correct way. So which one is correct?
>
> There was a discussion about this when we want to add TPL for Rockchip
> platform, Simon, Philipp
> and other people share there opinion , but I can't find it now, and
> people decide to follow:
> (TPL => SPL => U-Boot proper)

Thanks for providing more background information. This indeed matches
what Masahiro said about the preferred boot flow.

> Other than the README.TPL, I believe people also mention below presentation:
> https://www.denx.de/wiki/pub/U-Boot/MiniSummitELCE2013/tpl-presentation.pdf
>

Thanks for the link. This presentation looks to be written when TPL
was firstly introduced to U-Boot on Freescale PowerPC platforms. Its
contents matches what README.TPL says, but does not match what we
"decided" to follow later :)

Regards,
Bin