[U-Boot-Custodians] SPL / TPL

Wolfgang Denk wd at denx.de
Wed Oct 9 07:08:27 UTC 2019

Dear Masahiro,

In message <CAK7LNASUkH98Mh92UyXri_aPmOdsczN_vZWV-vXWiONUmDHXLg at mail.gmail.com> you wrote:
> I noticed some problems in the SPL framework
> because TPL corresponds to SPL of the 2-stage-boot platforms.

I understand what you mean, referring to the content or
configuration of such a boot stage.

> I pointed out TPL -> SPL -> U-Boot proper
> would make more sense.

NO, it would not, as the third step cannot preceed the secondf one.
Or rather should not in any sane system.

> TPL (let's say Tiny Program Loader) is a really small
> implementation for that platform,
> and SPL can re-use the common SPL framework.

I really dislike such bending and changing the interporetation of
long established terms.

We did not use any names that describe contents or size or whatever,
but rather program logic:

- The first thing to execute code on such systems is the RBL (ROM
  boot loader).
- It is followed by the SPL (Second boot loader).
- This may be folowed by a TPL (Third boot loader).
- This may be followed by U-Boot proper (or some OS, if you
  implement falcon boot mode).

So the naming refers to the sequence in which the stages are run,
and this _cannot_ be changed, as the 3rd step will always come
_after_ the 2nd one.

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
If you use modules, you pay the price. Sane embedded solutions
running in "tight" environments don't use modules :-)
    -- Benjamin Herrenschmidt in <1258234866.2140.451.camel at pasglop>

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