linux-kernel - Re: [PATCH v1 00/11] pstore: support crash log to block and mtd device

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Message-ID: <202002060108.7389A4C@keescook>
Date:   Thu, 6 Feb 2020 01:13:08 -0800
From:   Kees Cook <keescook@...omium.org>
To:     WeiXiong Liao <liaoweixiong@...winnertech.com>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Rob Herring <robh@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org
Subject: Re: [PATCH v1 00/11] pstore: support crash log to block and mtd
 device

On Mon, Jan 20, 2020 at 09:03:42AM +0800, WeiXiong Liao wrote:
> Why do we need to log to block (mtd) device?
> 1. Most embedded intelligent equipment have no persistent ram, which
>    increases costs. We perfer to cheaper solutions, like block devices.
> 2. Do not any equipment have battery, which means that it lost all data
>    on general ram if power failure. Pstore has little to do for these
>    equipments.
> 
> Why do we need mtdpstore instead of mtdoops?
> 1. repetitive jobs between pstore and mtdoops
>    Both of pstore and mtdoops do the same jobs that store panic/oops log.
> 2. do what a driver should do
>    To me, a driver should provide methods instead of policies. What MTD
>    should do is to provide read/write/erase operations, geting rid of codes
>    about chunk management, kmsg dumper and configuration.
> 3. enhanced feature
>    Not only store log, but also show it as files.
>    Not only log, but also trigger time and trigger count.
>    Not only panic/oops log, but also log recorder for pmsg, console and
>    ftrace in the future.

Hi! Sorry for the delay in my review of this series -- it's been a busy
couple of weeks for me. :) I'm still travelling this week, but I want to
give this a good review. I really like the idea of having a block device
backend for pstore; I'm excited to get this feature landed.

I think there may be a lot of redundancy between ramoops and the block
code in this series, but I suspect the refactoring of that can happen at
a later time. I'd like to get this reviewed and tested and see if I can
land it in the v5.7 merge window.

I hope to have time to focus on this next week once I'm back in my
normal timezone. ;)

Thanks again!

-Kees

-- 
Kees Cook