From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <4622729C.4080806@domain.hid>
Date: Sun, 15 Apr 2007 20:44:44 +0200
From: Wolfgang Grandegger <wg@domain.hid>
MIME-Version: 1.0
References: <461D65BC.2090406@domain.hid>
	<46220DC4.9040306@domain.hid>	<46222105.90900@domain.hid>
	<46226E16.9080004@domain.hid>
In-Reply-To: <46226E16.9080004@domain.hid>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: Re: [Xenomai-core] CAN_RAW, CAN_PROTO_RAW, and Socket-CAN
List-Id: "Xenomai life and development \(bug reports, patches,
	discussions\)" <xenomai.xenomai.org>
List-Unsubscribe: <https://mail.gna.org/listinfo/xenomai-core>,
	<mailto:xenomai-core-request@domain.hid>
List-Archive: </public/xenomai-core>
List-Post: <mailto:xenomai@xenomai.org>
List-Help: <mailto:xenomai-core-request@domain.hid>
List-Subscribe: <https://mail.gna.org/listinfo/xenomai-core>,
	<mailto:xenomai-core-request@domain.hid>
To: Wolfgang Grandegger <wg@domain.hid>
Cc: Jan Kiszka <jan.kiszka@domain.hid>, xenomai-core <xenomai@xenomai.org>

Wolfgang Grandegger wrote:
> Jan Kiszka wrote:
>> Wolfgang Grandegger wrote:
>>> Jan Kiszka wrote:
>>>> Hi Wolfgang,
>>>>
>>>> something is inconsistent about CAN_RAW in RT-Socket-CAN compared to
>>>> plain Socket-CAN. Also, the latter doesn't know any CAN_PROTO_xxx unless
>>>> I oversee something. Please have a look.
>>> There is CAN_PROTO_RAW defined and I have added some time ago CAN_RAW to
>>> rtcan.h to be compatible with Socket-CAN:
>>>
>>>   /** Particular CAN protocols
>>>    *
>>>    *  Currently only the RAW protocol is supported.
>>>    */
>>>   #define CAN_RAW  0
>> Yes, I know. But the question remains which way to go for rtcan:
>> Socket-CAN doesn't know CAN_PROTO_*, RT-Socket-CAN comes with CAN_RAW as
>> well now, but having a different value. That should be resolved, on
>> whatever side, IMHO.
> 
> Ah, now I understand your concern. CAN_PROTO_RAW actually serves the 
> same purpose then CAN_RAW defining the particular CAN protocol. I'm 
> going to clean it up soon removing CAN_PROTO_RAW and updating the doc. 
> CAN_PROTO_RAW was not used by any application, IIRC.

The man page for "socket" describes the protocol argument as shown below:

        The  protocol specifies a particular protocol to be used with the
        socket. Normally only a single protocol exists to support a
        particular socket  type within a given protocol family, in which
        case protocol can be specified as 0. However, it is possible that
        many  protocols  may exist, in which case a particular protocol
        must be specified in this manner.

A value of 0 is valid for RT-Socket-CAN but not for Socket-CAN. 
Therefore we need to define CAN_RAW=1 for compatibility reasons.

Wolfgang.