linux-kernel - Re: [EXT] Re: [PATCH 1/2] mmc: Support kmsg dumper based on pstore/blk

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Message-ID: <202012151232.843EB2CB49@keescook>
Date:   Tue, 15 Dec 2020 12:37:12 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Bhaskara Budiredla <bbudiredla@...vell.com>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Sunil Kovvuri Goutham <sgoutham@...vell.com>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>
Subject: Re: [EXT] Re: [PATCH 1/2] mmc: Support kmsg dumper based on
 pstore/blk

On Tue, Dec 15, 2020 at 12:42:58PM +0100, Ulf Hansson wrote:
> In principle, for non atomic path, I would rather see that the pstore
> file system should be able to be mounted on top of any generic block
> device partition - without requiring the block device driver to
> implement specific pstore ops.
> [...]
> Exactly. That's why I wonder if it's really worth it to support the
> panic writes at all.

pstore/blk already provides the generic hooking -- but it can't do
the panic write part (which that's very device/driver-specific). The
design was for individual backing devices to provide that directly
(which would needed read/write support too). And for those that don't
have panic/read/write support, they could still use the generic hooks
but they wouldn't be able to reliably (or at all?) catch panics (just
console writes, ftrace, pmsg, etc).

-- 
Kees Cook