From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Angeloni Andrea <andrea.angeloni@alfamationglobal.com>,
Alexander Stein <alexander.stein@systec-electronic.com>
Cc: "linux-can@vger.kernel.org" <linux-can@vger.kernel.org>
Subject: Re: BCM loopback - Information request
Date: Tue, 20 Sep 2016 17:06:42 +0200 [thread overview]
Message-ID: <0cbe9cab-e983-0439-e11d-bd59b8e2f32e@hartkopp.net> (raw)
In-Reply-To: <BECC71D675C45C4F912901A0BBE9A3A41493CDA1@srv-mail.DominioAlfa.local>
Hi Andrea,
the CAN_BCM sets the loopback by default:
http://lxr.linux.no/#linux+v4.7.4/net/can/bcm.c#L1229
So it is not configurable by now.
An possibility could be to implement socket options for the CAN_BCM so
that a setsockopt() with a new CAN_BCM_LOOPBACK becomes available.
But this is not in mainline Linux now.
Alternatively you can check for the fames you received on a CAN_RAW
socket whether these frames have been created on the local host:
http://lxr.linux.no/#linux+v4.7.4/Documentation/networking/can.txt#L632
Which means that you have to use recvmsg() to read from CAN_RAW.
'candump' does it here:
https://github.com/linux-can/can-utils/blob/master/candump.c#L793
Regards,
Oliver
On 09/20/2016 12:19 PM, Angeloni Andrea wrote:
> Ciao Alexander,
>
> thanks for your answer.
>
> Unfortunately, CAN_RAW_LOOPBACK is not working. Option is indeed referring to socket and not device, while BCM messages are coming from a different socket.
>
> Andrea
>
> -----Original Message-----
> From: Alexander Stein [mailto:alexander.stein@systec-electronic.com]
> Sent: martedì 20 settembre 2016 11:54
> To: Angeloni Andrea <andrea.angeloni@alfamationglobal.com>
> Cc: linux-can@vger.kernel.org
> Subject: Re: BCM loopback - Information request
>
> Hi Andrea,
>
> On Tuesday 20 September 2016 09:42:53, Angeloni Andrea wrote:
>> In my application there is a thread for each initialized CAN interface
>> that sends over TCP all the read data to a Windows Client. Data are
>> read using Socket RAW. Application is also capable to send cyclic
>> messages using Broadcast manager.
>>
>> Here is my question: how can I configure my application so that
>> reading thread does not get messages sent by BCM on the same interface?
>
> I think the socket option CAN_RAW_LOOPBACK is what you need. Please refer to
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/can.txt#n536
> You will not receive CAN frames sent from interface (BCM and other CAN frames), thus only messages from other CAN nodes.
>
> HTH
> Alexander
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
next prev parent reply other threads:[~2016-09-20 15:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-20 9:42 BCM loopback - Information request Angeloni Andrea
2016-09-20 9:53 ` Alexander Stein
2016-09-20 10:19 ` Angeloni Andrea
2016-09-20 15:06 ` Oliver Hartkopp [this message]
2016-09-20 15:19 ` Angeloni Andrea
2016-09-20 15:29 ` Oliver Hartkopp
2016-09-20 15:43 ` Angeloni Andrea
2016-09-21 13:35 ` Angeloni Andrea
2016-09-21 15:03 ` Angeloni Andrea
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