[PATCH v3 0/3] Add command to display or save Linux PStore dumps

Wolfgang Denk wd at denx.de
Fri Mar 20 09:08:42 CET 2020

Dear Heinrich,

In message <a1b7a877-e950-b09a-a0f6-2c9c9cb7e1fb at gmx.de> you wrote:
> > To me this sounds very much like what you are adding here (plus a
> > few features more).  Does it make sense to unify such code?
> It seems you are relating to
> https://lore.kernel.org/lkml/844oyrqvvb.fsf@sauna.l.org/t/

No, I'm not.  I was talking of my own code from many, many years

> ramoops in Linux is exactly doing what was suggested in 2009. You can
> find the Documentation/admin-guide/ramoops.rst

We had this in U-Boot long before that time.  It was a key
requirement when we added POST support in 2002.

> git grep -GHrn 'shared log' finds nothing in U-Boot. So if any part of
> the old implementation in U-Boot exists, could you, please, point us to
> the coding.

The shared log buffer support was added by commit 56f94be3ef63:

commit 56f94be3ef63732384063e110277ed89701b6471 (tag: LABEL_2002_11_05_1735)
Author: Wolfgang Denk <wdenk>
Date:   Tue Nov 5 16:35:14 2002 +0000

    * Add support for log buffer which can be passed to Linux kernel's
      syslog mechanism; used especially for POST results.

    * Patch by Klaus Heydeck, 31 Oct 2002:
      Add initial support for kup4k board

The code was mainly in common/cmd_log.c, but this got heahily
rewritten and is now in cmd/log.c ; apparently this got lost (like
the original copyright, sic!) when Simon modified / rewrote this

For history, try: git log --follow -- common/cmd_log.c

> If the original design never made it into Linux and there is an
> established Linux interface since 2011, I would plead to eliminate any
> remaining non-compliant coding from U-Boot should it exist.

I understand what Linus has is one-way, only focussing on crash
dump, i. e. it does not allow to pass information from U-Boot to Linux?

Also, my understanding is that the changes needed in Linux are
pretty small.

Maybe Heiko can comment on that...

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
Ken Dodd’s dad’s dog’s dead.

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