From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 18 Aug 2011 15:19:21 -0400
From: Andrew Tannenbaum <trb@domain.hid>
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Subject: Re: [Xenomai-help] odd code for loopback option in
	/src/utils/can/rtcansend.c
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To: xenomai@xenomai.org, Wolfgang Grandegger <wg@domain.hid>

Andrew Tannenbaum wrote:

> It looks like the default value for loopback is -1, and if you set it to
> 0 or 1, it turns loopback on, which seems strange. I don't understand
> rt_dev_setsockopt() fully, so I'm not sure if it's a bug - I don't know
> if -1 and 0 and 1 are three separate loopback states, but I think it
> merits attention. I think either the code is wrong or the help string
> and man page are not clear.

Ah, I see what it's doing.  It's changing an existing state, so there 
are three choices:

-1: no change
0: clear
1: set

So the code looks correct.

-Andy