Date:   Sun, 9 Aug 2020 16:21:29 +0300
From:   Moshe Shemesh <moshe@...lanox.com>
To:     Jakub Kicinski <kuba@...nel.org>, Jiri Pirko <jiri@...nulli.us>
Cc:     Jacob Keller <jacob.e.keller@...el.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Jiri Pirko <jiri@...lanox.com>,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Subject: Re: [PATCH net-next RFC 01/13] devlink: Add reload level option to
 devlink reload command


On 8/6/2020 9:25 PM, Jakub Kicinski wrote:
> On Wed, 5 Aug 2020 13:02:58 +0200 Jiri Pirko wrote:
>> Tue, Aug 04, 2020 at 10:39:46PM CEST, kuba@...nel.org wrote:
>>> AFAIU the per-driver default is needed because we went too low
>>> level with what the action constitutes. We need maintain the higher
>>> level actions.
>>>
>>> The user clearly did not care if FW was reset during devlink reload
>>> before this set, so what has changed? The objective user has is to
>> Well for mlxsw, the user is used to this flow:
>> devlink dev flash - flash new fw
>> devlink dev reload - new fw is activated and reset and driver instances
>> are re-created.
> Ugh, if the current behavior already implies fw-activation for some
> drivers then the default has to probably be "do all the things" :S


Okay, so devlink reload default for mlx5 will include also fw-activate 
to align with mlxsw default.

Meaning drivers that supports fw-activate will add it to the default.

The flow of devlink reload default on mlx5 will be:

If there is FW image pending and live patch is suitable to apply, do 
live patch and driver re-initialization.

If there is FW image pending but live patch doesn't fit do fw-reset and 
driver-initialization.

If no FW image pending just do driver-initialization.


I still think I should on top of that add the level option to be 
selected by the user if he prefers a specific action, so the uAPI would be:

devlink dev reload [ netns { PID | NAME | ID } ] [ level { fw-live-patch 
| driver-reinit |fw-activate } ]

But I am still missing something: fw-activate implies that it will 
activate a new FW image stored on flash, pending activation. What if the 
user wants to reset and reload the FW if no new FW pending ? Should we 
add --force option to fw-activate level ?


>>> activate their config / FW / move to different net ns.
>>>
>>> Reloading the driver or resetting FW is a low level detail which
>>> achieves different things for different implementations. So it's
>>> not a suitable abstraction -> IOW we need the driver default.
>> I'm confused. So you think we need the driver default?
> No, I'm talking about the state of this patch set. _In this patchset_
> we need a driver default because of the unsuitable abstraction.
>
> Better design would not require it.
>
>>> The work flow for the user is:
>>>
>>> 0. download fw to /lib/firmware
>>> 1. devlink flash $dev $fw
>>> 2. if live activation is enabled
>>>    yes - devlink reload $dev $live-activate
>>>    no - report machine has to be drained for reboot
>>>
>>> fw-reset can't be $live-activate, because as Jake said fw-reset does
>>> not activate the new image for Intel. So will we end up per-driver
>>> defaults in the kernel space, and user space maintaining a mapping from
>> Well, that is what what is Moshe's proposal. Per-driver kernel default..
>> I'm not sure what we are arguing about then :/
> The fact that if I do a pure "driver reload" it will active new
> firmware for mlxsw but not for mlx5. In this patchset for mlx5 I need
> driver reload fw-reset. And for Intel there is no suitable option.
>
>>> a driver to what a "level" of reset implies.
>>>
>>> I hope this makes things crystal clear. Please explain what problems
>>> you're seeing and extensions you're expecting. A list of user scenarios
>>> you foresee would be v. useful.

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