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

Frédéric Danis frederic.danis at collabora.com
Fri Mar 20 11:13:25 CET 2020

Hi Wolfgang, Heinrich, Heiko,

On 20/03/2020 09:08, Wolfgang Denk wrote:
> 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
> 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?

Yes, currently it is not possible to pass information from U-Boot to Linux.
But, PStore does not only store crash dump, but also console, ftrace and 
user space logs.

It may be possible to add a "bootloader" storage space to PStore.

Best regards,

Frédéric Danis

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