From: Eric Dumazet <eric.dumazet@gmail.com>
To: Bill F <falcigno@juno.com>
Cc: netdev@vger.kernel.org
Subject: Re: trying to set skb->tstamp before netif_rx did not work in tun/tap driver, 2.6.27
Date: Fri, 08 Jul 2011 07:45:00 +0200 [thread overview]
Message-ID: <1310103900.2517.2.camel@edumazet-laptop> (raw)
In-Reply-To: <loom.20110708T042440-631@post.gmane.org>
Le vendredi 08 juillet 2011 à 02:33 +0000, Bill F a écrit :
> Hi all,
>
> I am trying to set the receive timestamp for a packet in the tun/tap device
> driver before sending it into the network stack (by calling netif_rx_ni). On the
> application side I'm using recvmsg() to receive the timestamp along with the
> received packet.
>
> I expected that any non-zero skb->tstamp I set would be the value my
> application would see when it used recvmsg(), but a corrupted value is
> coming out.
> * If I hardcode skb->tstamp.tv64 to x7777777766666666
> then recvmsg() always gets x011afd371a82fcc0.
> * If I hardcode x4de684b100000000,
> then recvmsg always gets x4f5f96640f2d1608.
> * If I set a timestamp that a different process gave to the tun/tap driver
> (this is the goal), then recvmsg gets a corrupted version of that
> timestamp.
> * If I hardcode a zero tstamp,
> then an accurate timestamp comes out (but not precise enough for my
> project).
>
> The kernel build is 2.6.27.7, the architecture is MIPS, 64bit. Shouldn't this
> work? Do I need to apply any known patches?
>
> This arrangement worked last month in a similar setup: an e1000 driver
> setting tstamp before calling netif_receive_skb() in a 2.6.24 kernel and a
> 686 architecture, 32 bit.
>
You probably are hardcoding too much things ;)
The only portable tv64 value is the zero one.
Check CONFIG_KTIME_SCALAR on your config, and ktime_set()
implementations in include/linux/ktime.h
prev parent reply other threads:[~2011-07-08 5:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-08 2:33 trying to set skb->tstamp before netif_rx did not work in tun/tap driver, 2.6.27 Bill F
2011-07-08 5:45 ` Eric Dumazet [this message]
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