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

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Date:   Thu, 4 Nov 2021 13:07:52 +0000 (GMT)
From:   "Maciej W. Rozycki" <macro@...am.me.uk>
To:     Andrzej Pietrasiewicz <andrzej.p@...labora.com>
cc:     Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org,
        linux-input@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Jiri Slaby <jirislaby@...nel.org>, kernel@...labora.com
Subject: Re: [RFC] tty/sysrq: Add alternative SysRq key

On Thu, 4 Nov 2021, Andrzej Pietrasiewicz wrote:

> > Is F10 sensible default? Would it make sense to use something like
> > alt-shift-esc so that this can be enabled by default?
> 
> Why "alt-shift-esc" could be enabled by default? Do you mean to enable it for
> all systems regardless of whether they declare or don't declare KEY_SYSRQ
> in their 'keybit' bitmap?

 FWIW from my perspective it'll work better as a replacement rather than 
additional key combination.

 The reason for this is with their more recent laptops Lenovo in their 
infinite wisdom have placed the <PrintScreen> key (which in a traditional 
PS/2-keyboard manner produces <SysRq> when combined with <Alt>) in their 
keyboards between the right <Alt> and <Ctrl> keys.  With thumbs not being 
as accurate as other fingers (and the overall misdesign of the keyboard 
and touchpad interface) you can imagine how often I have inadvertently hit 
<SysRq> combined with a letter key, wreaking havoc to my system (and of 
course I want to keep the key enabled for times when I do need it).

 Also Documentation/admin-guide/sysrq.rst mentions that you can set an 
alternative keycode sequence for KEY_SYSRQ with `setkeycodes <sequence> 
99' already, but I find this pretty limiting as this only works for single 
keypresses rather than combinations of keys, because <sequence> actually 
refers to a single scancode (possibly 0xe0-prefixed).

  Maciej