>(1) It would be trivial to modify xtnpd and ntpd to do the right
>thing.  Long term, this is the right thing to do.

Is it trivial enough that you'll implement it and maintain a
nonstandard API forever?

>(2) It would also be trivial to implement the 'correct' API, then
>implement (as an MI tty ioctl, if you really really want it) the bogus
>interface as calls into the driver which use the 'better' ioctl
>interface.

I don't want to buy into maintaining our own nonstandard API in xntpd
and/or ntpd.

>I.e., make the long-term solution the 'right' one, and implement the
>gross short-term fix as a hack.

The DCD timestamping has to be done in the chipset-level code.  would
you really have the tty layer catch the TIODCDTIMESTAMP ioctl and
re-issue the two new ioctls to the chipset level code?