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vt: Add a note on the historical abuse of CLOCK_TICK_RATE 

This is one area where we can't just magic away the bizarre use of
CLOCK_TICK_RATE as it leaks to user space APIs. It also means the visible
CLOCK_TICK_RATE is frozen for architectures which is horrible.

We need to fix this somehow

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2009-05-06 17:17:26 +01:00 committed by Linus Torvalds
parent 413f81eba3
commit fab892232e
1 changed files with 6 additions and 0 deletions
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6
drivers/char/vt_ioctl.c
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@ -400,6 +400,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
case KIOCSOUND:
if (!perm)
goto eperm;
/* FIXME: This is an old broken API but we need to keep it
supported and somehow separate the historic advertised
tick rate from any real one */
if (arg)
arg = CLOCK_TICK_RATE / arg;
kd_mksound(arg, 0);
@ -417,6 +420,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
*/
ticks = HZ * ((arg >> 16) & 0xffff) / 1000;
count = ticks ? (arg & 0xffff) : 0;
/* FIXME: This is an old broken API but we need to keep it
supported and somehow separate the historic advertised
tick rate from any real one */
if (count)
count = CLOCK_TICK_RATE / count;
kd_mksound(count, ticks);