Messages in this thread | | | Date | Mon, 16 Feb 2015 06:14:35 +0100 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH 3/5] virtio: Don't expose legacy net features when VIRTIO_NET_NO_LEGACY defined. |
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> struct virtio_net_hdr hdr; > __virtio16 num_buffers; /* Number of merged rx buffers */ > }; > +#else /* ... VIRTIO_NET_NO_LEGACY */ > +/* > + * This header comes first in the scatter-gather list. If you don't > + * specify GSO or CSUM features, you can simply ignore the header. > + * > + * This is bitwise-equivalent to the legacy struct virtio_net_hdr_mrg_rxbuf.
I would add "but with all fields squashed into the main structure".
> + */ > +struct virtio_net_hdr_v1 { > +#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 /* Use csum_start, csum_offset */ > +#define VIRTIO_NET_HDR_F_DATA_VALID 2 /* Csum is valid */ > + __u8 flags; > +#define VIRTIO_NET_HDR_GSO_NONE 0 /* Not a GSO frame */ > +#define VIRTIO_NET_HDR_GSO_TCPV4 1 /* GSO frame, IPv4 TCP (TSO) */ > +#define VIRTIO_NET_HDR_GSO_UDP 3 /* GSO frame, IPv4 UDP (UFO) */ > +#define VIRTIO_NET_HDR_GSO_TCPV6 4 /* GSO frame, IPv6 TCP */ > +#define VIRTIO_NET_HDR_GSO_ECN 0x80 /* TCP has ECN set */ > + __u8 gso_type; > + __virtio16 hdr_len; /* Ethernet + IP + tcp/udp hdrs */ > + __virtio16 gso_size; /* Bytes to append to hdr_len per frame */ > + __virtio16 csum_start; /* Position to start checksumming from */ > + __virtio16 csum_offset; /* Offset after that to place checksum */ > + __virtio16 num_buffers; /* Number of merged rx buffers */ > +}; > +#endif /* ...VIRTIO_NET_NO_LEGACY */
I note that this way host code can't be structured like this:
struct virtio_net_hdr_v1 modern; /* handle modern guests */ ....
#ifndef VIRTIO_NET_NO_LEGACY struct virtio_net_hdr_mrg_rxbuf mrg; /* handle legacy guests */ #endif
Define virtio_net_hdr_v1 unconditionally?
> /* > * Control virtqueue data structures
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