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From: Joel Stanley <joel@jms.id.au>
To: Andrew Jeffery <andrew@aj.id.au>
Cc: OpenBMC Maillist <openbmc@lists.ozlabs.org>
Subject: Re: [PATCH 1/3] ARM: dts: rainier: Add reserved memory for ramoops
Date: Tue, 6 Oct 2020 03:22:18 +0000
Message-ID: <CACPK8Xd-3e+6EO1dz7aQZqTpxamDcVPfqAgbneg2_W=vpto3Kw@mail.gmail.com> (raw)
In-Reply-To: <20201002063414.275161-2-andrew@aj.id.au>

On Fri, 2 Oct 2020 at 06:35, Andrew Jeffery <andrew@aj.id.au> wrote:
>
> Reserve a 1MiB region of memory to record kmsg dumps and console state
> into 16kiB ring-buffer slots. The sizing allows for up to 32 dumps to be
> captured and read out.
>
> Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
> ---
>  arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts b/arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts
> index e6f422edf454..46a0e95049fd 100644
> --- a/arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts
> +++ b/arch/arm/boot/dts/aspeed-bmc-ibm-rainier.dts
> @@ -47,6 +47,14 @@ reserved-memory {
>                 #size-cells = <1>;
>                 ranges;
>
> +               ramoops@b7f00000 {
> +                       compatible = "ramoops";
> +                       reg = <0xb7f00000 0x100000>;
> +                       record-size = <0x4000>;
> +                       console-size = <0x4000>;

This is conserative. We've got plenty of space, how about we make it bigger?

$ git grep console-size *.dts* | grep -Po "0x([0-9]+)" | xargs printf
"%x\n" | sort -n
8000
8000
10000
10000
20000
20000
20000
20000
20000
60000
100000

The median is 128KB, which sounds reasonable.

$ git grep record-size *.dts* | grep -Po "0x([0-9]+)" | xargs printf "%x\n"
20000
400
400
20000
20000
20000
10000
10000
10000
10000
20000

64KB is the median record size.

> +                       pmsg-size = <0x4000>;

Do we want to add ftrace too?

Should we also add max-reason = KMSG_DUMP_EMERG?

Logging reboots and shutdowns is informative (you know if a reboot was
intentional or due to a crash that wasn't recorded) and allows for
testing.

Cheers,

Joel

> +               };
> +
>                 flash_memory: region@B8000000 {
>                         no-map;
>                         reg = <0xB8000000 0x04000000>; /* 64M */
> --
> 2.25.1
>

  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-02  6:34 [PATCH 0/3] Enable pstore for Rainier Andrew Jeffery
2020-10-02  6:34 ` [PATCH 1/3] ARM: dts: rainier: Add reserved memory for ramoops Andrew Jeffery
2020-10-06  3:22   ` Joel Stanley [this message]
2020-10-16  3:38     ` Andrew Jeffery
2020-10-06  4:25   ` Milton Miller II
2020-10-06  4:29     ` Andrew Jeffery
2020-10-06  4:44     ` Milton Miller II
2020-10-02  6:34 ` [PATCH 2/3] ARM: config: Enable PSTORE in aspeed_g5_defconfig Andrew Jeffery
2020-10-06  3:51   ` Joel Stanley
2020-10-02  6:34 ` [PATCH 3/3] ARM: dts: rainier: Don't shout addresses Andrew Jeffery
2020-10-06  3:51   ` Joel Stanley
2020-10-02  6:38 ` [PATCH 0/3] Enable pstore for Rainier Andrew Jeffery
2020-10-07  7:21 ` Joel Stanley
2020-10-10  2:50   ` Andrew Jeffery

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