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Date:   Fri, 30 Mar 2018 12:39:07 +0200
From:   Jiri Pirko <jiri@resnulli.us>
To:     Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Cc:     netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
        davem@davemloft.net, viro@zeniv.linux.org.uk,
        ebiederm@xmission.com, stephen@networkplumber.org,
        akpm@linux-foundation.org, torvalds@linux-foundation.org,
        ganeshgr@chelsio.com, nirranjan@chelsio.com, indranil@chelsio.com
Subject: Re: [PATCH net-next v2 1/2] fs/crashdd: add API to collect hardware
 dump in second kernel
Message-ID: <20180330103907.GC3313@nanopsycho>
References: <cover.1521888444.git.rahul.lakkireddy@chelsio.com>
 <296ffbd47fd4f30238689e636bd2480683224227.1521888444.git.rahul.lakkireddy@chelsio.com>
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Sat, Mar 24, 2018 at 11:56:33AM CET, rahul.lakkireddy@chelsio.com wrote:
>Add a new module crashdd that exports the /sys/kernel/crashdd/
>directory in second kernel, containing collected hardware/firmware
>dumps.
>
>The sequence of actions done by device drivers to append their device
>specific hardware/firmware logs to /sys/kernel/crashdd/ directory are
>as follows:
>
>1. During probe (before hardware is initialized), device drivers
>register to the crashdd module (via crashdd_add_dump()), with
>callback function, along with buffer size and log name needed for
>firmware/hardware log collection.
>
>2. Crashdd creates a driver's directory under
>/sys/kernel/crashdd/<driver>. Then, it allocates the buffer with

This smells. I need to identify the exact ASIC instance that produced
the dump. To identify by driver name does not help me if I have multiple
instances of the same driver. This looks wrong to me. This looks like
a job for devlink where you have 1 devlink instance per 1 ASIC instance.

Please see:
http://patchwork.ozlabs.org/project/netdev/list/?series=36524

I bevieve that the solution in the patchset could be used for
your usecase too.


>requested size and invokes the device driver's registered callback
>function.
>
>3. Device driver collects all hardware/firmware logs into the buffer
>and returns control back to crashdd.
>
>4. Crashdd exposes the buffer as a binary file via
>/sys/kernel/crashdd/<driver>/<dump_file>.
>