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

Wolfgang Denk
2020-03-20T08:08:42Z

Dear Heinrich,

In message <a1b7a877-e950-b09a-a0f6-2c9c9cb7e1fb@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 at sauna.l.org/t/

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

> 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
driver.

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

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