linux-kernel - Re: [PATCH] tty/sysrq: Add alternative SysRq key

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Date:   Fri, 26 Jun 2020 13:07:38 +0200
From:   Andrzej Pietrasiewicz <andrzej.p@...labora.com>
To:     Pavel Machek <pavel@...x.de>
Cc:     linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Jiri Slaby <jslaby@...e.com>, kernel@...labora.com
Subject: Re: [PATCH] tty/sysrq: Add alternative SysRq key

Hi Pavel,

W dniu 21.06.2020 o 23:21, Pavel Machek pisze:
> Hi!
> 
>> There exist machines which don't have SysRq key at all, e.g. chromebooks.
>>
>> This patch allows configuring an alternative key to act as SysRq. Devices
>> which declare KEY_SYSRQ in their 'keybit' bitmap continue using KEY_SYSRQ,
>> but other devices use the alternative SysRq key instead, by default F10.
>> Which key is actually used can be modified with sysrq's module parameter.
>>
>> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...labora.com>
> 
> So... SysRq was selected because you are not going to press
> Alt-Printscreen-X by default.

This patch does not change the Alt-PrintScreen/SysRq-something sequence.
What it does instead is making the 'PrintScreen/SysRq' component of the
sequence configurable for input devices which don't declare KEY_SYSRQ in
their 'keybit' bitmap, so the sequence becomes:

Alt-<alternative sysrq key>-something

If the alternative sysrq key is used (i.e. the input device in question
does not declare KEY_SYSRQ), it is F10 by default and _that_ can be changed
with the module parameter.

To summarize:

- devices which do declare KEY_SYSRQ must use Alt-PrintScreen/SysRq-something
- devices which don't declare KEY_SYSRQ must use Alt-F10-something, but F10
can be changed with a module parameter to something else

Regards,

Andrzej