Re: [PATCH 5/5] net/cxgbe: read firmware configuration file from filesystem

[Thomas Monjalon <thomas@monjalon.net>]

06/05/2022 13:36, Rahul Lakkireddy:
> The Chelsio FW config file contains a list of register=value pairs to
> change configuration of the NIC before firmware is initialized.
> It closely resembles the INI file format. It is mainly used to aid
> in debugging FW initialization failures and to optimally partition
> NIC hardware resources for specific requirements. Partitioning
> generally involves moving resources on unused Physical Functions
> (PFs) to the main PF, like redistributing queues, hardware TCAMs,
> etc., before firmware begins initialization. Once the configuration
> looks good, then the final FW config file is flashed onto the NIC
> using the cxgbtool. The FW config file can then be removed from the
> /lib/firmware/cxgb4/ directory and the FW will begin initializing
> with the flashed FW config file on the NIC from next time onwards.
> 
> With this patch, the FW config file is selected in following order.
> 
> 1) Check and select FW config file present in /lib/firmware/cxgb4/
>    directory.
> 
> 2) Otherwise, check and select FW config file flashed onto the
>    NIC.
> 
> 3) Otherwise, select the default FW config file embedded within the
>    FW binary on the NIC.
> 
> Since this is pretty low-level hardware configuration, the users are
> not expected to change this file without expert guidance. So,
> exporting such a low-level configuration via devargs API does not
> feel like the right fit for this specific requirement.
> 
> Once FW is up and running with the FW config file, some of the driver
> and FW runtime features can be enabled/disabled via devargs API during
> driver probe.
> 
> To summarize, the FW config file is intended to debug FW initialization
> failures and/or aid in resources partitioning before FW starts
> initialization. Once the FW is running, the whole or smaller slices
> of these partitioned resources can be further redistributed across
> the multiple physical ports controlled by the same underlying PF.

Sorry it is not clear to me.
The FW file is used by cxgbtool to flash it, right?
The PMD may use the same FW file for debug diagnostics?
How is it used by the kernel?