linux-kernel - Re: [PATCH] vt: Drop K_OFF for VC

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Date:	Wed, 12 Dec 2012 10:08:19 -0800
From:	Arthur Taylor <art@...ed.ca>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Adam Jackson <ajax@...hat.com>, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] vt: Drop K_OFF for VC_MUTE

>> Drop the K_OFF handling and replace it with a new "mute" ioctl pair.
>> Anybody using K_OFF would already need to be prepared to handle it
>> throwing -EINVAL for old kernel compatibility, so userspace will degrade
>> gracefully.
>
> Interesting theory. It may degrade but it'll degrade to a state worse
> than current.

AFAIK  the only consumer of K_OFF is Xorg, as I wrote both the
patches, and Xorg will degrade nicely if K_OFF doesn't work.

I'm confused why g-c-c is trying to set the virtual console keyboard
mode, as it is completely the wrong thing to do. X never wants its
virtual console set to K_UNICODE, which is the same as K_XLATE, but in
unicode. Doing so causes the kernel to buffer lines and handle things
like CTRL-C and ALT-Fn.

As this is a per-virtual console setting, setting it on the current VT
where X is running has no effect on other virtual consoles.

Modern X uses the input event subsystem directly and has no need for
the virtual console to be involved with input. Ancient X required that
the virtual console be in K_RAW.

-Art
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