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tty: Add a new VT mode which is like VT_PROCESS but doesn't require a VT_RELDISP ioctl call

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This new VT mode (VT_PROCESS_AUTO) does everything that VT_PROCESS does
except that it doesn't wait for a VT_RELDISP ioctl before switching
away from a VT with that mode.

If the X server eventually uses this new mode, debugging and crash
recovery should become easier. This is because even when currently in
the VT of a frozen X server it would still be possible to switch out
by doing SysRq-r and then CTRL-<number of a text vt>, sshing in and
doing chvt <number of a text vt>, or any other method of VT switching.
The general concensus on #xorg-devel seems to be that it should be
safe to use this with X now that we have KMS.

This also moves the VT_ACKACQ define to a more appropriate place,
for clarity's sake.

Signed-off-by: Ari Entlich <atrigent@ccs.neu.edu>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Ari Entlich
2010-02-19 09:37:55 -05:00
committed by Greg Kroah-Hartman
parent d9661adfb8
commit eec9fe7d1a
2 changed files with 22 additions and 20 deletions
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3
include/linux/vt.h
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@@ -27,7 +27,7 @@ struct vt_mode {
#define VT_SETMODE 0x5602 /* set mode of active vt */
#define VT_AUTO 0x00 /* auto vt switching */
#define VT_PROCESS 0x01 /* process controls switching */
#define VT_ACKACQ 0x02 /* acknowledge switch */
#define VT_PROCESS_AUTO 0x02 /* process is notified of switching */
struct vt_stat {
unsigned short v_active; /* active vt */
@@ -38,6 +38,7 @@ struct vt_stat {
#define VT_SENDSIG 0x5604 /* signal to send to bitmask of vts */
#define VT_RELDISP 0x5605 /* release display */
#define VT_ACKACQ 0x02 /* acknowledge switch */
#define VT_ACTIVATE 0x5606 /* make vt active */
#define VT_WAITACTIVE 0x5607 /* wait for vt active */