netdev - Re: wilc1000 MAC address is 00:00:00:00:00:00

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Message-ID: <2d548e01b266f7b1ad19a5ea979d00bf@walle.cc>
Date:   Thu, 09 Feb 2023 22:19:01 +0100
From:   Michael Walle <michael@...le.cc>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Ajay.Kathat@...rochip.com, heiko.thiery@...il.com,
        Claudiu.Beznea@...rochip.com, kvalo@...nel.org,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        Amisha.Patel@...rochip.com
Subject: Re: wilc1000 MAC address is 00:00:00:00:00:00

Am 2023-02-09 22:07, schrieb Jakub Kicinski:
> On Thu, 9 Feb 2023 18:51:58 +0000 Ajay.Kathat@...rochip.com wrote:
>> > netdev should be created with a valid lladdr, is there something
>> > wifi-specific here that'd prevalent that? The canonical flow is
>> > to this before registering the netdev:
>> 
>> Here it's the timing in wilc1000 by when the MAC address is available 
>> to
>> read from NV. NV read is available in "mac_open" net_device_ops 
>> instead
>> of bus probe function. I think, mostly the operations on netdev which
>> make use of mac address are performed after the "mac_open" (I may be
>> missing something).
>> 
>> Does it make sense to assign a random address in probe and later read
>> back from NV in mac_open to make use of stored value?
> 
> Hard to say, I'd suspect that may be even more confusing than
> starting with zeroes. There aren't any hard rules around the
> addresses AFAIK, but addrs are visible to user space. So user
> space will likely make assumptions based on the most commonly
> observed sequence (reading real addr at probe).

Maybe we should also ask the NetworkManager guys. IMHO random
MAC address sounds bogus.

I don't understand the "we load the firmware when the interface
is brought up" thing. Esp. with network manager scanning in the
background, the firmware gets loaded so many times.

-michael