Re: [PATCH V5 2/6 net-next] netdevice.h: Add zero-copy flag in netdevice

Ben Hutchings
2011-05-16T19:35:18Z

On Mon, 2011-05-16 at 12:28 -0700, Shirley Ma wrote:
> Signed-off-by: Shirley Ma <xma@us.ibm.com>
> ---
>
> include/linux/netdevice.h | 10 ++++++++++
> 1 files changed, 10 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index a134d80..2646251 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -1066,6 +1066,16 @@ struct net_device {
> #define NETIF_F_NOCACHE_COPY (1 << 30) /* Use no-cache copyfromuser */
> #define NETIF_F_LOOPBACK (1 << 31) /* Enable loopback */
>
> +/*
> + * Bit 31 is for device to map userspace buffers -- zerocopy
> + * Device can set this flag when it supports HIGHDMA.
> + * Device can't recycle this kind of skb buffers.
> + * There are 256 bytes copied, the rest of buffers are mapped.
> + * The userspace callback should only be called when last reference to this skb
> + * is gone.
> + */
> +#define NETIF_F_ZEROCOPY (1 << 31)

Sorry, bit 31 is taken. You get the job of turning features into a
wider bitmap.

Ben.

--
Ben Hutchings, Senior Software Engineer, Solarflare
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