Re: Magic Alt-SysRq change in 2.6.18-rc1

[Chuck Ebbert <76306.1226@compuserve.com>]

In-Reply-To: <Pine.LNX.4.44L0.0607091657490.28904-100000@netrider.rowland.org>

On Sun, 9 Jul 2006 17:06:57 -0400, Alan Stern wrote:
> 
> <...> changes in the behavior of Alt-SysRq?
> 
> Before 2.6.18-rc1, I used to be able to use it as follows:
> 
>       Press and hold an Alt key,
>       Press and hold the SysRq key,
>       Release the Alt key,
>       Press and release some hot key like S or T or 7,
>       Repeat the previous step as many times as desired,
>       Release the SysRq key.
> 
> This scheme doesn't work any more, or if it does, the timing requirements
> are now much stricter.  In practice I have to hold down all three keys at
> the same time; I can't release the Alt key before pressing the hot key.


Look at the change history for keyboard.c:


[PATCH] fix magic sysrq on strange keyboards

Magic sysrq fails to work on many keyboards, particulary most of notebook
keyboards.  This patch fixes it.

The idea is quite simple: Discard the SysRq break code if Alt is still being
held down.  This way the broken keyboard can send the break code (or the user
with a normal keyboard can release the SysRq key) and the kernel waits until
the next key is pressed or the Alt key is released.


-- 
Chuck
 "You can't read a newspaper if you can't read."  --George W. Bush