It sitll works but MAGIC_SYSRQ has to be compiled in your kernel.
Controlling the use of SysRq keys
There are some ways of controlling the use of SysRq keys(i.e. what can be used, enabling or disabling them completely), two ways of doing this are:-
1) Configuring the SysRq keys during kernel compilation itself.
There isn’t much here since you can only disable SysRq keys and not actually control or define what you can and can’t use. The option you are looking for is:-
2) Using proc sysrq trigger calls.
This is much more flexible than changing the configuration of the kernel but this has one downside with security which is explained after(since it is very minor). You use the echo command to achieve this for ease but you could also use any normal text editor to achieve this. Now the command is(you will need root permissions):-
echo * > /proc/sys/kernel/sysrqwhere “*” is a number, which can be any one of these:-
0 – disable sysrq keys completely
1 – enable all functions of sysrq
2 – enable control of console logging level
4 – enable control of keyboard (SAK, unraw)
8 – enable debugging dumps of processes etc.
16 – enable sync command
32 – enable remount read-only
64 – enable signalling of processes (term, kill, oom-kill)
128 – allow reboot/poweroff
256 – allow nicing of all RT tasks(control the nice level(priority) of Real Time tasks)
So you can define what SysRq keys can be used, and also define whether they are all on or off.
Now for the “downside”. For example you disable SysRq keys when you want to stop people(local) from doing key presses and then shutting down or messing up the PC during an important task. Now with configuring the kernel, you can stop SysRq keys from being used at all from the beginning of the boot process right uptil the end, with calling the proc sysrq triggers however, your option only takes place when it is executed(i.e. after the system has booted up) so there is a certain area of vulnerability with calling the triggers whereas there is no such thing in configuring the kernel, some people are that desperate to secure their systems to care about a few seconds, however do not blame me for it.
If it doesn't work I would assume it is either not in the kernel or is disabled by something like selinux or some other security feature.