linux-kernel - Re: [PATCH] tty: Add NULL TTY driver

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Message-ID: <de23cde3-c77f-cdbf-0968-d7f44c723120@metux.net>
Date:   Fri, 5 Apr 2019 14:32:41 +0200
From:   "Enrico Weigelt, metux IT consult" <lkml@...ux.net>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>, jslaby@...e.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: Add NULL TTY driver

On 05.04.19 11:00, Vincent Whitchurch wrote:
> On Fri, Apr 05, 2019 at 10:39:43AM +0200, Enrico Weigelt, metux IT consult wrote:
>> On 03.04.19 16:11, Vincent Whitchurch wrote:
>>
>>> Especially on embedded systems, it would be convenient to have a simple
>>> way to disable the console (both for kernel and userspace) on a system
>>> which normally uses it, to free up the UART for other things.
>>
>> Just symlinking to /dev/null does not work ?
> 
> No, /dev/null does not support the TTY ioctls.

hmm, wo (which programs) do you need, that really need them ?

>> OTOH, if you're introducing a dummy console, wouldn't a ringbuffer that,
>> can be read out later, a better option ?
> 
> There is already a ttyprintk driver in mainline to send these messages
> to the printk ring buffer if one is actually intrested in what is
> written to the console.  There's no option to enable it via console= in
> mainline but I have a patch for that too.

Great. IMHO, that would be the better way.


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@...ux.net -- +49-151-27565287