serial ports on the Ultra 5

Marius Strobl marius at
Mon Dec 5 19:01:51 GMT 2005

On Mon, Dec 05, 2005 at 10:25:42AM -0800, Aaron Glenn wrote:
> For the life of me I cannot get either serial port on one of my Ultra
> 5's to work in FreeBSD. I'll admit I don't quite grasp how the sio(4),
> puc(4), and sab(4) drivers intertwine (if at all...) and while
> /etc/ttys makes sense to me, I don't understand how to get or why I
> don't have a /dev entry for either of the serial ports. I am unable to
> console out or into the box; prior to FreeBSD 6.0 the machine had
> OpenBSD and the ports worked flawlessly, ruling out a hardware issue.
> The release notes say it should work, the sab(4) man pages says
> /dev/tty[a-b], /etc/ttys has an entry, dmesg says puc(4), and I can't
> make heads or tails of anything. I'm missing something important - can
> a kind soul point me to it?

The only driver for RS232 controllers you are using is uart(4).
Its device nodes are /dev/ttyuN and /dev/cuauN. On an U5 (and
most other sun4u machines) unit 0 is the serial port A, unit 1
is port B, unit 2 is the keyboard port (no device node is created
for this one) and unit 3 is the mouse port.
Puc(4) is only used to split or multiplex the resources of the
SCCs (Serial Communication Controller, sort of a dual-UART) used
in sun4u machines so uart(4) can attach to both of the two channels
of a SCC separately.
Sab(4) is deprecated and superseded by uart(4). It is disabled in
GENERIC since FreeBSD 5.4 and will go away at some point.
Sio(4) never really worked on sparc64. The devices supported by
sio(4) are also supported by uart(4).


This mail was scanned by AntiVir Milter.
This product is licensed for non-commercial use.
See for details.

More information about the freebsd-sparc64 mailing list