Jarod Wilson wrote:
> On Tue, Sep 06, 2016 at 04:55:29PM -0700, David Miller wrote:
>> From: Jarod Wilson <ja...@redhat.com>
>> Date: Fri, 2 Sep 2016 13:07:42 -0400
>>
>>> In any case, the number of "mtu < 68" and "#define FOO_MIN_MTU 68", or
>>> variations thereof, under drivers/net/ is kind of crazy.
>>
>> Agreed, we can have a default and let the different cases provide
>> overrides.
>>
>> Mostly what to do here is a function of the hardware though.
>
> So I've been tinkering with this some, and it looks like having both
> centralized min and max checking could be useful here. I'm hacking away at
> drivers now, but the basis of all this would potentially look about like
> the patch below, and each device would have to set dev->m{in,ax}_mtu one
> way or another. Drivers using alloc_etherdev and/or ether_setup would get
> the "default" values, and then they can be overridden. Probably need
> something to make sure dev->max_mtu isn't set to 0 though...
>
> Possibly on the right track here, or might there be a better way to
> approach this?
>
> diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
> index 117d02e..864d6f2 100644
> --- a/include/uapi/linux/if_ether.h
> +++ b/include/uapi/linux/if_ether.h
> @@ -35,6 +35,8 @@
> #define ETH_FRAME_LEN 1514 /* Max. octets in frame sans
> FCS */
> #define ETH_FCS_LEN 4 /* Octets in the FCS */
>
> +#define ETH_MIN_MTU 68 /* Min IPv4 MTU per RFC791 */
> +
> /*
> * These are the defined Ethernet Protocol ID's.
> */
Why don't we disable IPv4 if the MTU is lower than this value
as we do for IPv6?
--
Hideaki Yoshifuji <hideaki.yoshif...@miraclelinux.com>
Technical Division, MIRACLE LINUX CORPORATION
