intel ethernet: Use ether_gen_addr

[kbowling]

Summary

Use ether_gen_addr for mac generation

[kbowling]

@jrtc27 is there any issue to CHERI with the ether_addr cast like this? It is __packed.

[jrtc27]

In D31616#713099, @kbowling wrote:

@jrtc27 is there any issue to CHERI with the ether_addr cast like this? It is __packed.

No, that should be fine, the only time packed causes issues is when it's on structs that contain pointers (including intptr_t). I don't know why ether_addr is packed though, it just contains a byte array, packed is redundant.

[imp]

sys/dev/e1000/if_em.c

1080

I think this type punning is OK and well defined. The ether_addr structure is just an array of 6 bytes for the array, and hw->mac.addr provides 6 bytes of storage. __packed on the ether_addr structure should keep this well defined.

[imp]

In D31616#713101, @jrtc27 wrote:

I don't know why ether_addr is packed though, it just contains a byte array, packed is redundant.

I think it may date from the pre-EABI days of ARM where it did really weird things with structure padding. I suspect it can be dropped, but conservatism and the fact there will be little gain from dropping it has kept people from doing so...

[kevans]

Thanks!