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linux: Use K_OFF VT KB mode over K_RAW if available.

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Linux kernels since 2.6.38 (March 2011) have an VT KB mode K_OFF in
which special keys (like Ctrl+C) are not interpreted and input is not
buffered. Use of this mode over K_RAW removes the need for a
xf86ConsoleHandler to drain the VT input buffer, removing the grief it
causes when it goes wrong or is (de)initialized out-of-order. (This
also saves a few needless context switches per key event.)

If K_OFF is not defined or not understood by the kernel, K_RAW and the
previous method is used as a fall-back.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Arthur Taylor <art@ified.ca>
Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Arthur Taylor 2012-01-06 07:21:37 +00:00 committed by Keith Packard
parent 0b113f7cdf
commit ff891bbf68
1 changed files with 13 additions and 6 deletions
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19
hw/xfree86/os-support/linux/lnx_init.c
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@ -212,10 +212,20 @@ xf86OpenConsole(void)
tcgetattr(xf86Info.consoleFd, &tty_attr);
SYSCALL(ioctl(xf86Info.consoleFd, KDGKBMODE, &tty_mode));
SYSCALL(ret = ioctl(xf86Info.consoleFd, KDSKBMODE, K_RAW));
#ifdef K_OFF
/* disable kernel special keys and buffering */
SYSCALL(ret = ioctl(xf86Info.consoleFd, KDSKBMODE, K_OFF));
if (ret < 0)
FatalError("xf86OpenConsole: KDSKBMODE K_RAW failed %s\n",
strerror(errno));
#endif
{
SYSCALL(ret = ioctl(xf86Info.consoleFd, KDSKBMODE, K_RAW));
if (ret < 0)
FatalError("xf86OpenConsole: KDSKBMODE K_RAW failed %s\n",
strerror(errno));
/* need to keep the buffer clean, else the kernel gets angry */
xf86SetConsoleHandler(drain_console, NULL);
}
nTty = tty_attr;
nTty.c_iflag = (IGNPAR | IGNBRK) & (~PARMRK) & (~ISTRIP);
@ -228,9 +238,6 @@ xf86OpenConsole(void)
cfsetospeed(&nTty, 9600);
tcsetattr(xf86Info.consoleFd, TCSANOW, &nTty);
/* need to keep the buffer clean, else the kernel gets angry */
xf86SetConsoleHandler(drain_console, NULL);
/* we really should have a InitOSInputDevices() function instead
* of Init?$#*&Device(). So I just place it here */
}