netdev - Re: [PATCH net-next v2] eth: fbnic: Add support to write TCE TCAM entries

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Message-ID: <e2c12a98-acf3-46df-8831-4b898387bfa0@gmail.com>
Date: Thu, 31 Oct 2024 15:13:40 -0700
From: Mohsin Bashir <mohsin.bashr@...il.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: netdev@...r.kernel.org, alexanderduyck@...com, kuba@...nel.org,
 andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
 pabeni@...hat.com, kernel-team@...a.com, sanmanpradhan@...a.com,
 sdf@...ichev.me, vadim.fedorenko@...ux.dev, hmohsin@...a.com
Subject: Re: [PATCH net-next v2] eth: fbnic: Add support to write TCE TCAM
 entries

On 10/31/24 5:43 AM, Andrew Lunn wrote:
> On Wed, Oct 30, 2024 at 05:51:53PM -0700, Mohsin Bashir wrote:
>> Hi Andrew,
>>
> 
>> Basically, in addition to the RX TCAM (RPC) that you mentioned, we
>> also have a TCAM on the TX path that enables traffic redirection for
>> BMC. Unlike other NICs where BMC diversion is typically handled by
>> firmware, FBNIC firmware does not touch anything host-related. In
>> this patch, we are writing MACDA entries from the RPC (Rx Parser and
>> Classifier) to the TX TCAM, allowing us to reroute any host traffic
>> destined for BMC.
> 
> Two TCAMs, that makes a bit more sense.
> 
> But why is this hooked into set_rx_mode? It is nothing to do with RX.

We are trying to maintain a single central function to handle MAC updates.

> I assume you have some mechanism to get the MAC address of the BMC. I
> would of thought you need to write one entry into the TCAM during
> probe, and you are done?
> 
> 	Andrew

Actually, we may need to write entries in other cases as well. The fact 
that the BMC can come and go independently of the host would result in 
firmware notifying the host of the resulting change. Consequently, the 
host would need to make some changes that will be added in the following 
patch(es).