Subject: Re: [PATCH 4/4] lguest: Use GSO/IFF_VNET_HDR extensions on tun/tap

From: Anthony Liguori <[email-masked]>
Date: Wed, 25 Jun 2008 14:07:18 -0500

Rusty Russell wrote:
> @@ -1563,6 +1561,16 @@ static void setup_tun_net(char *arg)
>  	/* Tell Guest what MAC address to use. */
>  	add_feature(dev, VIRTIO_NET_F_MAC);
>  	add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);
> +	/* Expect Guest to handle everything except UFO */
> +	add_feature(dev, VIRTIO_NET_F_CSUM);

You're setting this feature twice.

> +	add_feature(dev, VIRTIO_NET_F_GUEST_CSUM);

You set this feature, but I never see the virtio-net driver acknowledge 
the feature.  Curiously, my implementation with KVM is struggling 
because UDP packet checksums are not correct so the DHCP client is 
ignoring them.  If I disable CSUM offload, things it works fine (using 
the virtio-net header).  The problem is only host=>guest, guest=>host is 
fine.

Regards,

Anthony Liguori