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From: Grant Edwards <>
Subject: Re: [Bug 1001466] /dev/null serial driver
Date: Thu, 16 Feb 2012 14:01:00 -0000	[thread overview]
Message-ID: <jhj25i$ies$> (raw)
In-Reply-To: <>

On 2012-02-16, <> wrote:

>> As you can see /dev/null is not some terminal line (serial device).
>> Well, eCos != *nix, but, I would avoid the ability to configure the
>> /dev/null as a serial device under eCos.
> Opengroup says (
> /dev/null An infinite data source and data sink. Data written to
> /dev/null shall be discarded. Reads from /dev/null shall always
> return end-of-file (EOF).

That makes no sense.  It not an infinite data source if a read always

> AFAIK there is no specific requirements regarding the implementation,
> only the name and the result it must provide. Using the serial
> abstraction seemed fine to me since most often /dev/null is used to
> sink data coming from a byte stream.

The issue is that "byte stream" and "serial device" are not
equivalent.  A "serial device" supports read/write like a byte stream,
but it also includes another API that.  On Unix, /dev/null isn't a
serial device, and that's why using that name for a serial device on
eCos is a possible source of confusion.  Historically, there has never
been a "null" serial device on Unix systems (that I know of).

> I suppose that serial devices are embedded in all targets, at least
> for diag_printf(), that why I placed it here so there is no need to
> bring other components.

I don't think anybody is arguing that a null serial device is a bad
idea, just that it might be better to use a name other than /dev/null.

>> Mess #3
>>   IMO, if anyone will see those words together in CDL (I mean 'serial'
>>   and 'null'), under eCos dev/serial/null, then he would think, Great!
>>   There is 'nullmodem' device in eCos! Come check my guess
>>   And after reading your documentation, they will think, Nope! They
>>   provide something very special (special null device :-)
> Well the name '/dev/null' is known for decades and for any *nix
> developer this name tells what it does, as posix/opengroup use this
> name.

Except on Unix, /dev/null is not a serial device (it's not a tty). 
It's a plain vanilla character device.

> I just need to sink data, I don't need a FIFO that copies data
> between two points, I don't need a cross-over serial cable. I need
> /dev/null :-)

If all you need is /dev/null, why the extra work to make it a serial

Grant Edwards               grant.b.edwards        Yow! I'm totally DESPONDENT
                                  at               over the LIBYAN situation
                                and the price of CHICKEN

  reply	other threads:[~2012-02-16 14:01 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-27 17:39 [Bug 1001466] New: " bugzilla-daemon
2012-01-27 19:14 ` [Bug 1001466] " bugzilla-daemon
2012-02-15 13:47 ` bugzilla-daemon
2012-02-15 13:48 ` bugzilla-daemon
2012-02-15 20:46 ` bugzilla-daemon
2012-02-16  9:55 ` bugzilla-daemon
2012-02-16 14:01   ` Grant Edwards [this message]
2012-02-16 12:20 ` bugzilla-daemon
2012-02-16 14:21 ` bugzilla-daemon
2012-02-16 15:06 ` bugzilla-daemon
2012-02-16 15:39 ` bugzilla-daemon
2012-02-16 15:58 ` bugzilla-daemon
2012-02-16 16:26 ` bugzilla-daemon
2012-02-16 16:37 ` bugzilla-daemon
2012-02-16 16:49 ` bugzilla-daemon
2012-02-16 17:21 ` bugzilla-daemon
2012-02-17  6:17 ` bugzilla-daemon
2012-02-18 19:38 ` bugzilla-daemon

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