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Message-Id: <1186746907.24669.107.camel@localhost.localdomain>
Date: Fri, 10 Aug 2007 13:55:07 +0200
From: Unai Uribarri <unai.uribarri@...enet.com>
To: Evgeniy Polyakov <johnpol@....mipt.ru>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] af_packet: don't enable timestamps in mmap'ed
sockets
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@...enet.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.
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