MPSAFE TTY schedule [uart vs sio]

[Takahashi Yoshihiro]

In article <29489C48-93A2-41D9-9EF1-5395A673A9B3 at mac.com>
Marcel Moolenaar <xcllnt at mac.com> writes:

> > The uart probably works for some 16550 based devices but does not work
> > for other one like multi-port devices.
> 
> The design principle of uart(4) is that it does not know
> about multi-port hardware. It controls a single serial
> port only. For multi-port hardware you must have multiple
> nodes on a bus or use an umbrella driver, such as puc(4),
> quicc(4) or scc(4). Those drivers provide attachments for
> every port.
> 
> I suspect that support for multi-port devices is not to
> hard to do on pc98...

Many serial devices on pc98 use indirect I/O space, so resource
management is quite complex.  Therefore, it may need more work you
think.

At the starting point, I have added CBus frontend and fixed console
support for pc98.

http://home.jp.freebsd.org/~nyan/patches/uart_pc98.diff.bz2

---
TAKAHASHI Yoshihiro <nyan at jp.FreeBSD.org>