Re: [PATCH 1/1] af_packet: don't enable timestamps in mmap'ed sockets

[Unai Uribarri <unai.uribarri@optenet.com>]

On vie, 2007-08-10 at 12:34 +0400, Evgeniy Polyakov wrote:
> Hi Unai.
> 
> On Thu, Aug 09, 2007 at 08:44:21PM +0200, Unai Uribarri (unai.uribarri@optenet.com) wrote:
> > There is another option:
> > 
> > 1. Move timestampt activation to packet_set_ring(), so it's activated
> > only once at setup instead of every time a packet arrives.
> 
> Does this break existing systems which expects timestamp be turned on
> always if there are packet sockets.
> 

Well, current behaviour is that all packets get always timestamped if
the socket has a reception ring. We are just activating it a bit sooner
at the setsockopt(SOL_PACKET, PACKET_RX_RING) call instead of waiting
until the reception of the first packet. And current applications can't
disable it if we use a new socket option. So I can see how an
application can break.

> > 2. Fix sock_setsockopt() so setting SO_TIMESTAMP to 0 effectively
> > disables timestamp.
> 
> This breaks compatibility. Add new socket option, which will really
> disable it and do all your logic, but not breaking existing
> applications.
> 

Is SO_TIMESTAMP2 a valid name? I can't imagine how to call it.