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SubjectMAGIC_SYSRQ problem: Do USB keyboards generate scancode 0x54

Hi all,

I have come across two USB keyboards that do not generate
the scancode 0x54 (== default SYSRQ_KEY) with Alt-PrtSc (SysRq).
These are a SGI USB keyboard and the Microsoft USB Natural keyboard.
Kind of makes it difficult to get MAGIC_SYSRQ to work.
The SGI keyboard is particularly weird as the key with (numbersign,
asciitilde) generates 0x54!

(Scancodes generated by Alt-PrtSc are the scancodes for Alt and PrtSc).

Is this typical of all USB keyboards??

I would like to propose that the SYSRQ_KEY be determined on the fly
by the sysrq_enabled kernel variable. (After all it is currently only
used as a on/off flag - by leveraging its actual variable one
can adapt to different weirdo keyboards without a kernel recompile.)

Scenario:

In a default setting:

echo "84" > /proc/sys/kernel/sysrq
# 84 = keycode of SysRq
With a USB keyboard without scancode 0x54, switch SYSRQ_KEY to PrtSc

echo "99" > /proc/sys/kernel/sysrq
# 99 = keycode of PrtSc

Comments? If this is a viable idea I will submit a patch.








Chan Shih-Ping (Richard) <cshihpin@dso.org.sg>
DSO National Laboratories
20 Science Park Drive
Singapore 118230
Key fingerprint = EA3D 4BCB CF7B 8B41 A42D FAB5 3098 C5A6 0DBE 78F2


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