linux-kernel - Re: [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops DT node

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Date:   Mon, 18 May 2020 16:45:32 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Pavel Tatashin <pasha.tatashin@...een.com>,
        Petr Mladek <pmladek@...e.com>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Benson Leung <bleung@...omium.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops
 DT node

On Fri, May 15, 2020 at 12:44 PM Kees Cook <keescook@...omium.org> wrote:
>
> From: Pavel Tatashin <pasha.tatashin@...een.com>

Subject still has 'max_reason'.

>
> Currently, it is possible to dump kmsges for panic, or oops.
> With max_reason it is possible to dump messages for other

And here.

> kmesg_dump events, for example reboot, halt, shutdown, kexec.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> Link: https://lore.kernel.org/lkml/20200506211523.15077-6-keescook@chromium.org/
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  .../devicetree/bindings/reserved-memory/ramoops.txt | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/reserved-memory/ramoops.txt b/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
> index 0eba562fe5c6..b7886fea368c 100644
> --- a/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
> +++ b/Documentation/devicetree/bindings/reserved-memory/ramoops.txt
> @@ -30,7 +30,7 @@ Optional properties:
>  - ecc-size: enables ECC support and specifies ECC buffer size in bytes
>    (defaults to 0: no ECC)
>
> -- record-size: maximum size in bytes of each dump done on oops/panic
> +- record-size: maximum size in bytes of each kmsg dump.
>    (defaults to 0: disabled)
>
>  - console-size: size in bytes of log buffer reserved for kernel messages
> @@ -45,7 +45,16 @@ Optional properties:
>  - unbuffered: if present, use unbuffered mappings to map the reserved region
>    (defaults to buffered mappings)
>
> -- no-dump-oops: if present, only dump panics (defaults to panics and oops)
> +- max-reason: if present, sets maximum type of kmsg dump reasons to store
> +  (defaults to 2: log Oopses and Panics). This can be set to INT_MAX to
> +  store all kmsg dumps. See include/linux/kmsg_dump.h KMSG_DUMP_* for other
> +  kmsg dump reason values. Setting this to 0 (KMSG_DUMP_UNDEF), means the
> +  reason filtering will be controlled by the printk.always_kmsg_dump boot
> +  param: if unset, it will be KMSG_DUMP_OOPS, otherwise KMSG_DUMP_MAX.
> +
> +- no-dump-oops: deprecated, use max_reason instead. If present, and
> +  max_reason is not specified, it is equivalent to max_reason = 1

And here (3 times).

> +  (KMSG_DUMP_PANIC).
>
>  - flags: if present, pass ramoops behavioral flags (defaults to 0,
>    see include/linux/pstore_ram.h RAMOOPS_FLAG_* for flag values).
> --
> 2.20.1
>