netdev - Re: [PATCH v2 0/3] devlink region trigger support

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Date:   Mon, 13 Jan 2020 10:16:51 -0800
From:   Jacob Keller <jacob.e.keller@...el.com>
To:     Jakub Kicinski <kubakici@...pl>,
        Yunsheng Lin <linyunsheng@...wei.com>
Cc:     Alex Vesker <valex@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "jiri@...nulli.us" <jiri@...nulli.us>
Subject: Re: [PATCH v2 0/3] devlink region trigger support

On 1/13/2020 3:34 AM, Jakub Kicinski wrote:
> On Mon, 13 Jan 2020 09:39:50 +0800, Yunsheng Lin wrote:
>> I am not sure I understand "live region" here, what is the usecase of live
>> region?
> 
> Reading registers of a live system without copying them to a snapshot
> first. Some chips have so many registers it's impractical to group them
> beyond "registers of IP block X", if that. IMHO that fits nicely with
> regions, health is grouped by event, so we'd likely want to dump for
> example one or two registers from the MAC there, while the entire set
> of MAC registers can be exposed as a region.
> 

Right. I'm actually wondering about this as well. Region snapshots are
captured in whole and stored and then returned through the devlink
region commands.

This could be problematic if you wanted to expose a larger chunk of
registers or addressable sections of flash contents, as the size of the
contents goes beyond a single page.

If we instead focus regions onto the live-read aspect, the API can
simply be a request to read a segment of the region. Then, the driver
could perform the read of that chunk and report it back.