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authorDaniel P. Berrange <berrange@redhat.com>2017-10-19 15:28:43 +0100
committerGerd Hoffmann <kraxel@redhat.com>2017-10-23 10:50:02 +0200
commit620775d1d8ec4e7e5d3dc6807a9355d6b15cc01d (patch)
treeecf62954253b2445250510d18d027f5f64021441 /hw/input/trace-events
parent237925baa9dd9aaa0bcbe1a506346a0c1e7d208b (diff)
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ps2: fix scancodes sent for Alt-Print key combination (aka SysRq)
The 'Print' key is special in the AT set 1 / set 2 scancode definitions. An unmodified 'Print' key is supposed to send AT Set 1: e0 2a e0 37 (Down) e0 b7 e0 aa (Up) AT Set 2: e0 12 e0 7c (Down) e0 f0 7c e0 f0 12 (Up) which QEMU gets right. When pressed in combination with the 'Alt_L' or 'Alt_R' keys (which signify SysRq), the scancodes are required to follow a different scheme. With Alt_L, the expected sequences are AT set 1: 38, 54 (Down) d4, b8 (Up) AT set 2: 11, 84 (Down) f0 84, f0 11 (Up) And with Alt_R AT set 1: e0 38, 54 (Down) d4, e0 b8 (Up) AT set 2: e0 11, 84 (Down) f0 84, f0 e0 11 (Up) It is actually slightly more complicated than that, because (according results of 'showkey -s', keyboards will in fact first release the currently pressed modifier before sending the sequence above (which effectively re-presses & then releases the modifier) and finally re-press the original modifier afterwards. IOW, with Alt_L we need to send AT set 1: b8, 38, 54 (Down) d4, b8, 38 (Up) AT set 2: f0 11, 11, 84 (Down) f0 84, f0 11, 11 (Up) And with Alt_R AT set 1: e0 b8, e0 38, 54 (Down) d4, e0 b8, e0 38 (Up) AT set 2: e0 f0 11, e0 11, 84 (Down) f0 84, e0 f0 11, e0 11 (Up) The AT set 3 scancodes have no special handling for Alt-Print. Rather than fixing the handling of the 'print' key in the ps2 driver to consider the Alt modifiers, way back, a patch was commited that defined an extra 'sysrq' key name: commit f2289cb6924afc97b2a75d21bfc9217024d11741 Author: balrog <balrog@c046a42c-6fe2-441c-8c8c-71466251a162> Date: Wed Jun 4 10:14:16 2008 +0000 Add sysrq to key names known by "sendkey". Adding sysrq keycode to the table enabling running sysrq debugging in the guest via the monitor sendkey command, like: (qemu) sendkey alt-sysrq-t Tested on x86-64 target and Linux guest. Signed-off-by: Ryan Harper <ryanh@us.ibm.com> With this patch QEMU would send AT set 1: 38, 54 (Down) d4, b8 (Up) AT set 2: 11, 84 (Down) f0 84, f0 11 (Up) but this doesn't match what actual real keyboards send, as it is not releasing the original modifier & pressing it again afterwards. In addition the original problem remains, and a new problem was added: - The sequence 'alt-print-t' is still broken, acting as if 'print-t' was requested - The sequence 'sysrq-t' is broken, injecting an undefine scancode sequence tot he guest os (bare 0x54) To deal with this mess we make these changes to the ps2 code, so that we track the state of modifier keys (Alt, Shift, Ctrl - both left & right). Then we can vary what scancodes are sent for Q_KEY_CODE_PRINT according to the Alt key modifier state Interestingly, it appears that of operating systems I've checked (Linux, FreeBSD and OpenSolaris), none of them actually bother to validate the full sequences for a unmodified 'Print' key. They all just ignore the leading "e0 2a" and trigger based off "e0 37" alone. The latter two byte sequence is what keyboards send with 'Print' is combined with 'Shift' or 'Ctrl' modifiers. Signed-off-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 20171019142848.572-5-berrange@redhat.com Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'hw/input/trace-events')
-rw-r--r--hw/input/trace-events1
1 files changed, 1 insertions, 0 deletions
diff --git a/hw/input/trace-events b/hw/input/trace-events
index d04132d..88150ef 100644
--- a/hw/input/trace-events
+++ b/hw/input/trace-events
@@ -2,6 +2,7 @@
# hw/input/ps2.c
ps2_put_keycode(void *opaque, int keycode) "%p keycode 0x%02x"
+ps2_keyboard_event(void *opaque, int qcode, int down, unsigned int modifier, unsigned int modifiers) "%p qcode %d down %d modifier 0x%x modifiers 0x%x"
ps2_read_data(void *opaque) "%p"
ps2_set_ledstate(void *s, int ledstate) "%p ledstate %d"
ps2_reset_keyboard(void *s) "%p"