[ofa-general] Re: IPoIB NETIF_F_SG flag for GSO

[Michael S. Tsirkin]

> Quoting Shirley Ma <xma at us.ibm.com>:
> Subject: Re: IPoIB NETIF_F_SG flag for GSO
> 
> Hello Michael,
> 
> > Yes. SG currently needs csum offloading, and IPoIB does not
> > support that.
> 
> SG should have nothing to do with CSUM. They are two different features, one is
> for scatter/gather IO, one is HW can checksum all the packets. If you look at
> net device feature, NETIF_F_SG & NETIF_F_HW_CSUM are different flags.

Look at register_netdevice:
       /* Fix illegal SG+CSUM combinations. */
        if ((dev->features & NETIF_F_SG) &&
            !(dev->features & NETIF_F_ALL_CSUM)) {
                printk(KERN_NOTICE "%s: Dropping NETIF_F_SG since no checksum feature.\n",
                       dev->name);
                dev->features &= ~NETIF_F_SG;
        }

> What did you get when enabling IPoIB SG? I rememerbed there was a discussion in
> net-dev before.
> 
> Thanks
> Shirley Ma

Google it.

-- 
MST