On Mon, Aug 04, 2003 at 10:30:09PM +0200, Quentin Garnier wrote:
> Le Mon, 4 Aug 2003 12:51:42 +0200
> Manuel Bouyer a ecrit :
> > > > > But anyway, we don't have to check if the NIC can receive the
> > > > > frame at that time, because obviously it could.
> > > > 
> > > > ec_capenable ETHERCAP_VLAN_MTU is there to have the driver allow the
> > > > nic to receive such frames. 
> > > 
> > > I'll do that then.
> > 
> > Thanks.
> 
> I tested this with sip(4). I added the necessary bit to tlp(4), but I
> didn't have the time to test it yet. I'll have a closer look at all the
> other cards I have here (ne, rtk, ep, iy). None of them declare the
> ETHERCAP_VLAN_MTU. My guess is that there is no documentation and/or no
> way to disallow or permit reception of large frames.

ne use the dp8390.c code, which declares it.
For rtk, I guess nobody looked at it yet.

> Index: sys/net/if_ether.h
> ===================================================================
> RCS file: /cvsroot/src/sys/net/if_ether.h,v
> retrieving revision 1.33
> diff -u -r1.33 if_ether.h
> --- sys/net/if_ether.h	2003/06/26 08:22:06	1.33
> +++ sys/net/if_ether.h	2003/08/04 15:37:44
> @@ -60,6 +60,9 @@
>   * Some Ethernet extensions.
>   */
>  #define	ETHER_VLAN_ENCAP_LEN 4	/* length of 802.1Q VLAN encapsulation */
> +#ifdef PPPOE_ACCEPT_LARGE_FRAMES
> +#define	ETHER_PPPOE_ENCAP_LEN 8
> +#endif
>  
>  /*
>   * Ethernet address - 6 octets
> @@ -90,10 +93,18 @@
>   * Compute the maximum frame size based on ethertype (i.e. possible
>   * encapsulation) and whether or not an FCS is present.
>   */
> +#ifdef PPPOE_ACCEPT_LARGE_FRAMES
>  #define	ETHER_MAX_FRAME(ifp, etype, hasfcs)				\
>  	((ifp)->if_mtu + ETHER_HDR_LEN +				\
>  	 ((hasfcs) ? ETHER_CRC_LEN : 0) +				\
> +	 (((etype) == ETHERTYPE_VLAN) ? ETHER_VLAN_ENCAP_LEN : 0) +	\
> +	 (((etype) == ETHERTYPE_PPPOE) ? ETHER_PPPOE_ENCAP_LEN : 0))
> +#else
> +#define ETHER_MAX_FRAME(ifp, etype, hasfcs)				\
> +	((ifp)->if_mtu + ETHER_HDR_LEN +				\
> +	 ((hasfcs) ? ETHER_CRC_LEN : 0) +				\
>  	 (((etype) == ETHERTYPE_VLAN) ? ETHER_VLAN_ENCAP_LEN : 0))
> +#endif
>  
>  /*
>   * Ethernet CRC32 polynomials (big- and little-endian verions).
> @@ -170,6 +181,9 @@
>  #define	ETHERCAP_VLAN_MTU	0x00000001	/* VLAN-compatible MTU */
>  #define	ETHERCAP_VLAN_HWTAGGING	0x00000002	/* hardware VLAN tag support */
>  #define	ETHERCAP_JUMBO_MTU	0x00000004	/* 9000 byte MTU supported */
> +#ifdef PPPOE_ACCEPT_LARGE_FRAMES
> +#define	ETHERCAP_PPPOE_MTU	0x00000008	/* 1508 byte MTU supported */
> +#endif
>  
>  #ifdef	_KERNEL
>  extern u_int8_t etherbroadcastaddr[ETHER_ADDR_LEN];
> Index: sys/net/if_pppoe.c
> ===================================================================
> RCS file: /cvsroot/src/sys/net/if_pppoe.c,v
> retrieving revision 1.44
> diff -u -r1.44 if_pppoe.c
> --- sys/net/if_pppoe.c	2003/06/27 16:24:32	1.44
> +++ sys/net/if_pppoe.c	2003/08/04 15:37:45
> @@ -830,6 +830,14 @@
>  			sc->sc_eth_if = ifunit(parms->eth_ifname);
>  			if (sc->sc_eth_if == NULL)
>  				return ENXIO;
> +#ifdef PPPOE_ACCEPT_LARGE_FRAMES
> +			if (sc->sc_eth_if->if_type == IFT_ETHER) {
> +				/* It shouldn't be anything else anyway */
> +				struct ethercom *ec = (struct ethercom *)sc->sc_eth_if;
> +				if ((ec->ec_capabilities & ETHERCAP_PPPOE_MTU))
> +					ec->ec_capenable |= ETHERCAP_PPPOE_MTU;
> +			}
> +#endif

If you enable ETHERCAP_PPPOE_MTU, then you probably want to change the MTU
of pppoe from 1492 to 1500.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 24 ans d'experience feront toujours la difference
--