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>

drivers/char/vt_ioctl.c

@@ -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);