[ipxe-devel] [PATCH 2/3] igbvf: Assign random MAC address if none is set

[Michael Brown]

On 02/06/14 07:02, Hannes Reinecke wrote:
> On 06/02/2014 12:36 AM, Michael Brown wrote:
>>
>> +    if ( is_valid_ether_addr( netdev->hw_addr )) {
>> +        memcpy ( adapter->hw.mac.addr, netdev->hw_addr, ETH_ALEN);
>> +    }
>> +
>>       mac->ops.init_hw ( hw );
>>
>>       if ( is_valid_ether_addr(adapter->hw.mac.addr) ) {
>>
>> What does this code do?
>>
> Well, in theory it should be possible to change the mac address via
> commands; the doc says something like
>
> ifclose net0
> set net0/mac XXX
> ifopen net0

OK, understood.  The expected data flow is:

- the probe() function fills in netdev->hw_addr

- when the probe function calls register_netdev(), the contents of 
netdev->hw_addr are used to populate netdev->ll_addr

- netdev->ll_addr is exposed as ${net0/mac}, and can be updated while 
the network device is closed via iPXE commands

- when the network device is opened, the open() function should program 
the receiver with the current MAC address taken from netdev->ll_addr.


Therefore:

- netdev->hw_addr holds the "hardware address" (i.e. the address 
retrieved from the EEPROM or equivalent).  The driver's probe() function 
should fill in this address before calling register_netdev().

- netdev->ll_addr holds the current link-layer address.  The driver's 
open() function should apply this address to the NIC.

Michael