Messages in this thread Patch in this message | | | Date | Sun, 30 Jan 2011 00:36:22 -0800 | Subject | [PATCH] vt: Add virtual console keyboard mode OFF | From | Arthur Taylor <> |
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Add a new mode for the virtual console keyboard OFF to compliment RAW in which all key events are ignored. New mode prevents vt input buffers from overflowing when a program opens but doesn't read from a tty, like Xorg using only evdev for input.
The new mode is available by the ioctl KDSKBMODE with argument K_OFF from linux/kd.h. Does not effect sysrq behaviour.
Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Alan Cox <alan@redhat.com> Signed-off-by: Arthur Taylor <art@ified.ca> --- drivers/tty/vt/keyboard.c | 5 +++-- drivers/tty/vt/vt_ioctl.c | 3 +++ include/linux/kbd_kern.h | 3 ++- include/linux/kd.h | 1 + 4 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index e95d787..6dd3c68 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -654,7 +654,8 @@ static void k_spec(struct vc_data *vc, unsigned char value, char up_flag) if (value >= ARRAY_SIZE(fn_handler)) return; if ((kbd->kbdmode == VC_RAW || - kbd->kbdmode == VC_MEDIUMRAW) && + kbd->kbdmode == VC_MEDIUMRAW || + kbd->kbdmode == VC_OFF) && value != KVAL(K_SAK)) return; /* SAK is allowed even in raw mode */ fn_handler[value](vc); @@ -1295,7 +1296,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw) if (rc == NOTIFY_STOP) return;
- if (raw_mode && type != KT_SPEC && type != KT_SHIFT) + if ((raw_mode || kbd->kbdmode == VC_OFF) && type != KT_SPEC && type != KT_SHIFT) return;
(*k_handler[type])(vc, keysym & 0xff, !down); diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c index 1235ebd..6bcf05b 100644 --- a/drivers/tty/vt/vt_ioctl.c +++ b/drivers/tty/vt/vt_ioctl.c @@ -688,6 +688,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, kbd->kbdmode = VC_UNICODE; compute_shiftstate(); break; + case K_OFF: + kbd->kbdmode = VC_OFF; + break; default: ret = -EINVAL; goto out; diff --git a/include/linux/kbd_kern.h b/include/linux/kbd_kern.h index 506ad20..4b0761c 100644 --- a/include/linux/kbd_kern.h +++ b/include/linux/kbd_kern.h @@ -50,11 +50,12 @@ struct kbd_struct { #define VC_CAPSLOCK 2 /* capslock mode */ #define VC_KANALOCK 3 /* kanalock mode */
- unsigned char kbdmode:2; /* one 2-bit value */ + unsigned char kbdmode:3; /* one 3-bit value */ #define VC_XLATE 0 /* translate keycodes using keymap */ #define VC_MEDIUMRAW 1 /* medium raw (keycode) mode */ #define VC_RAW 2 /* raw (scancode) mode */ #define VC_UNICODE 3 /* Unicode mode */ +#define VC_OFF 4 /* disabled mode */
unsigned char modeflags:5; #define VC_APPLIC 0 /* application key mode */ diff --git a/include/linux/kd.h b/include/linux/kd.h index 15f2853..c36d847 100644 --- a/include/linux/kd.h +++ b/include/linux/kd.h @@ -81,6 +81,7 @@ struct unimapinit { #define K_XLATE 0x01 #define K_MEDIUMRAW 0x02 #define K_UNICODE 0x03 +#define K_OFF 0x04 #define KDGKBMODE 0x4B44 /* gets current keyboard mode */ #define KDSKBMODE 0x4B45 /* sets current keyboard mode */
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