netdev - Re: [PATCH v7] igb: Assign random MAC address instead of fail in case of invalid one

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Message-ID: <4576ee79-1040-1998-6d91-7ef836ae123b@gmail.com>
Date:   Wed, 14 Dec 2022 22:43:12 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>, Leon Romanovsky <leon@...nel.org>
Cc:     Lixue Liang <lianglixuehao@....com>, anthony.l.nguyen@...el.com,
        linux-kernel@...r.kernel.org, jesse.brandeburg@...el.com,
        davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        netdev@...r.kernel.org, lianglixue@...atwall.com.cn,
        Alexander H Duyck <alexander.duyck@...il.com>
Subject: Re: [PATCH v7] igb: Assign random MAC address instead of fail in case
 of invalid one

On 14.12.2022 21:50, Jakub Kicinski wrote:
> On Wed, 14 Dec 2022 20:53:30 +0200 Leon Romanovsky wrote:
>> On Wed, Dec 14, 2022 at 08:51:06AM -0800, Jakub Kicinski wrote:
>>> On Wed, 14 Dec 2022 09:22:13 +0200 Leon Romanovsky wrote:  
>>>> NAK to any module driver parameter. If it is applicable to all drivers,
>>>> please find a way to configure it to more user-friendly. If it is not,
>>>> try to do the same as other drivers do.  
>>>
>>> I think this one may be fine. Configuration which has to be set before
>>> device probing can't really be per-device.  
>>
>> This configuration can be different between multiple devices
>> which use same igb module. Module parameters doesn't allow such
>> separation.
> 
> Configuration of the device, sure, but this module param is more of 
> a system policy. BTW the name of the param is not great, we're allowing
> the use of random address, not an invalid address.
> 
>> Also, as a user, I despise random module parameters which I need
>> to set after every HW update/replacement.
> 
> Agreed, IIUC the concern was alerting users to incorrect EEPROM values.
> I thought falling back to a random address was relatively common, but
> I haven't done the research.

My 2ct, because I once added the fallback to a random MAC address to r8169:
Question is whether there's any scenario where you would prefer bailing out
in case of invalid MAC address over assigning a random MAC address (that the
user may manually change later) plus a warning.
I'm not aware of such a scenario. Therefore I decided to hardcode this
fallback in the driver.