netdev - Re: [RFC PATCH net-next v2 6/6] devlink: add overwrite mode to flash update

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Date:   Mon, 20 Jul 2020 12:09:53 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jacob Keller <jacob.e.keller@...el.com>
Cc:     netdev@...r.kernel.org, Jakub Kicinski <kubakici@...pl>,
        Tom Herbert <tom@...bertland.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Michael Chan <michael.chan@...adcom.com>,
        Bin Luo <luobin9@...wei.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Leon Romanovsky <leon@...nel.org>,
        Ido Schimmel <idosch@...lanox.com>,
        Danielle Ratson <danieller@...lanox.com>
Subject: Re: [RFC PATCH net-next v2 6/6] devlink: add overwrite mode to flash
 update

Fri, Jul 17, 2020 at 08:35:41PM CEST, jacob.e.keller@...el.com wrote:
>A flash image may contain settings or device identifying information.
>When performing a flash update, these settings and information may
>conflict with contents already in the flash. Devices may handle this
>conflict in multiple ways.
>
>Add a new attribute to the devlink command,
>DEVLINK_ATTR_FLASH_UPDATE_OVERWRITE_MODE, which specifies how the device
>should handle these settings and fields.
>
>DEVLINK_FLASH_UPDATE_OVERWRITE_NOTHING, the default, requests that all
>settings and device identifiers within the current flash are kept. That
>is, no settings or fields will be overwritten. This is the expected
>behavior for most updates, and appears to be how all of the drivers are
>implemented today.
>
>DEVLINK_FLASH_UPDATE_OVERWRITE_SETTINGS, requests that the device
>overwrite any device settings in the flash section with the settings
>from the flash image, but to preserve identifiers such as the MAC
>address and serial identifier. This may be useful as a way to restore
>a device to known-good settings from a new flash image.
>
>DEVLINK_FLASH_UPDATE_OVERWRITE_EVERYTHING, requests that all content in
>the flash image be preserved over content of flash on the device. This
>mode requests the device to completely overwrite the flash section,
>possibly changing settings and device identifiers. The primary
>motivation is to support writing initial device identifiers during
>manufacturing. It is not expected to be necessary in normal end-user
>flash updates.
>
>For the ice driver, implement support for the overwrite mode by
>selecting the associated preservation level to request from firmware.
>
>For all other drivers that support flash update, require that the mode
>be DEVLINK_FLASH_UPDATE_OVERWRITE_NOTHING, which is the expected
>default.
>
>Update the documentation to explain the overwrite mode attribute.

This looks odd. You have a single image yet you somehow divide it
into "program" and "config" areas. We already have infra in place to
take care of this. See DEVLINK_ATTR_FLASH_UPDATE_COMPONENT.
You should have 2 components:
1) "program"
2) "config"

Then it is up to the user what he decides to flash.