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

From: Rob Herring <robh+dt@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Petr Mladek <pmladek@suse.com>, Tony Luck <tony.luck@intel.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Anton Vorontsov <anton@enomsg.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	devicetree@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	Colin Cross <ccross@android.com>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Benson Leung <bleung@chromium.org>
Subject: Re: [PATCH v4 6/6] ramoops: Add max_reason optional field to ramoops DT node
Date: Mon, 18 May 2020 16:45:32 -0600	[thread overview]
Message-ID: <CAL_JsqLVgdUEP74nJOHOBD2abK=3YfCqX9GmL2iXdPNctcRdjw@mail.gmail.com> (raw)
In-Reply-To: <20200515184434.8470-7-keescook@chromium.org>

On Fri, May 15, 2020 at 12:44 PM Kees Cook <keescook@chromium.org> wrote:
>
> From: Pavel Tatashin <pasha.tatashin@soleen.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@soleen.com>
> Link: https://lore.kernel.org/lkml/20200506211523.15077-6-keescook@chromium.org/
> Signed-off-by: Kees Cook <keescook@chromium.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
>