Re: Getting a stable MAC address for a RPI CM3+ with ue0 interface

On 9/20/23 22:02, Mike Karels wrote:
> On 20 Sep 2023, at 14:49, Patrick M. Hausen wrote:
> 
>> Hi all,
>>
>> some more research ...
>>
>>> Am 20.09.2023 um 21:05 schrieb Patrick M. Hausen <pmh@hausen.com>:
>>> No worky.
>>> [...]
>>
>>
>> I could not find any code in the network startup routines in userland that
>> would generate and configure a random MAC address. So I looked for
>> the driver.
>>
>> Apparently the TuringPi uses smsc(4), and there we have it straight from
>> the driver source:
>>
>> -------------------
>> static void
>> smsc_attach_post(struct usb_ether *ue)
>> {
>> [...]
>>   /* Attempt to get the mac address, if an EEPROM is not attached this
>> * will just return FF:FF:FF:FF:FF:FF, so in such cases we invent a MAC
>> * address based on urandom.
>> */
>> [...]
>>   /* Initialise the chip for the first time */
>> smsc_chip_init(sc);
>> }
>> -------------------
>>
>> So what we would really need is a tunable - one per driver or possibly a
>> common one read and acted upon by all of the USB ethernet drivers ...
> 
> There is a routine called ether_gen_addr(), which will generate an
> Ethernet MAC based on the hostid and the interface name, both of which
> are reasonably stable.  Not very many drivers use it though.  It
> would probably be an improvement.
> 
>> With no code on our side to perform anything, no wonder the RPI
>> config files have no effect.
> 
> It would seem wrong to me to have USB Ethernet drivers using an RPI-specific
> mechanism.
> 
>> Dang. That's frustrating. With aarch64 having been promoted to "tier 1"
>> I really expected full support for all RPI platforms and related features
>> and hardware.
>>
>> Or am I misreading that? I though that the Pi was *the* aarch64 platform,
>> at least in numbers ...
> 
> In numbers, probably.  In support, no.
> 
> 		Mike
> 
>> Kind regards,
>> Patrick
> 


Would this work?

diff --git a/sys/dev/usb/net/if_smsc.c b/sys/dev/usb/net/if_smsc.c
index 0a0268bfa1a2..4a7983a20717 100644
--- a/sys/dev/usb/net/if_smsc.c
+++ b/sys/dev/usb/net/if_smsc.c
@@ -1554,6 +1554,7 @@ static void
  smsc_attach_post(struct usb_ether *ue)
  {
         struct smsc_softc *sc = uether_getsc(ue);
+       struct ether_addr eaddr;
         uint32_t mac_h, mac_l;
         int err;
  
@@ -1589,9 +1590,10 @@ smsc_attach_post(struct usb_ether *ue)
                         err = usb_fdt_get_mac_addr(sc->sc_ue.ue_dev, &sc->sc_ue);
  #endif
                 if ((err != 0) || (!ETHER_IS_VALID(sc->sc_ue.ue_eaddr))) {
-                       read_random(sc->sc_ue.ue_eaddr, ETHER_ADDR_LEN);
-                       sc->sc_ue.ue_eaddr[0] &= ~0x01;     /* unicast */
-                       sc->sc_ue.ue_eaddr[0] |=  0x02;     /* locally administered */
+                       device_printf(ue->ue_dev, "No MAC address found. Using ether_gen_addr().\n");
+                       ether_gen_addr(ue->ue_ifp, &eaddr);
+                       for (int i = 0; i < ETHER_ADDR_LEN; i++)
+                               sc->sc_ue.ue_eaddr[i] = eaddr.octet[i];
                 }
         }


I don't have the hardware so I can't test it.

Regards,
Ronald.