linux-kernel - Re: [PATCH 0/4] TTY: fix Caps Lock LED

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Message-ID: <20170127184758.GB3298@var.home>
Date:   Fri, 27 Jan 2017 19:47:58 +0100
From:   Samuel Thibault <samuel.thibault@...-lyon.org>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] TTY: fix Caps Lock LED

Benjamin Tissoires, on Fri 27 Jan 2017 19:34:36 +0100, wrote:
> On Jan 27 2017 or thereabouts, Samuel Thibault wrote:
> > > So by default, on Fedora and RHEL at least*, the Caps Lock LED is broken while
> > > in a VT.
> > 
> > Yes, and in Debian too, see
> > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514464
> > That was the trigger for my kbd LED work.
> 
> Do you have a full working solution? Instead of me trying to reinvent
> the wheel?

The one described in comment

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514464#114

Anton hasn't implemented it in console-setup yet, but I don't think his
code would be reusable as such by ckbcomp anyway.

> > > I tracked down the issue to be a change in ckbcomp introduced because
> > > the kernel just can't properly handle all keymaps. However, if the keymap now
> > > works thanks to the work around in place, the LED just doesn't.
> > 
> > Yes, and ckbcomp now just has to properly set the LED trigger for
> > capslock. Something like:
> > 
> > echo kbd-ctrlllock > /sys/class/leds/input0::capslock/trigger
> 
> Ack, but there are 3 (solvable) issues:
> - in Fedora/RHEL, ckbcomp is used statically when creating the kbd
>   package, the keymaps are generated and then forgot. So ckbcomp is not
>   the component to fix for us

But it can emit a file which says which modifier is used for capslock.

> - you need to trigger this for each keyboard that appears on the bus.
>   This can be achieved by a udev rule, but...
> - ... if you blindly set a udev rule to change the trigger, you just
>   break every users who manually call loadkeys with a non-patched caps
>   lock (when forcing a legacy keymap).

The file I mentioned above could be actually inlined in what loadkeys
eats.

Samuel