SysRq (RSEIUB) problems

I’ve set this up on both my desktops and it works as expected and is good to have.

I’m now trying on a another device which has only a bluetooth keyboard and no ‘PrintScrn/SysRq’ key. but i have two keys I won’t use and have been trying to remap keycodes without success.

First of all sysrq is enabled

 $ cat /proc/sys/kernel/sysrq
 1

One spare key is Super_L

KeyPress event, serial 37, synthetic NO, window 0x4600001,
    root 0x379, subw 0x0, time 9206985, (192,-323), root:(1063,124),
    state 0x0, keycode 133 (keysym 0xffeb, Super_L), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

And I can map another symbol to that key, and in the case below it prints the ‘colon’ :

sudo xmodmap -e "keysym Super_L = colon"

But I can’t get SysRq working that way, I’ve tried different using different names, PRSC, Print, Sys_Rq, etc etc but non are working. Once I get it to work I was going to use an autostart script to map it

Any pointers as to what I can try next?

Edit

I found the keysym name is Sys_Req and

sudo xmodmap -e "keysym Super_L = Sys_Req"

now gives

KeyPress event, serial 34, synthetic NO, window 0x5000001,
    root 0x379, subw 0x0, time 3076608, (490,23), root:(1070,444),
    state 0x0, keycode 133 (keysym 0xff15, Sys_Req), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

But still REISUB still not working…