sio3 (COM4) problems on FreeBSD 4.8-RELEASE

[Malcolm Kay]

On Tue, 14 Oct 2003 01:37, Jesse Guardiani wrote:
> Howdy list,
>
> I'm having trouble with my sio3 (/dev/cuaa3) port on one
> of my servers (with an SMP kernel). When I try to `tip com4`
> to a cisco switch using this port, I get only partial data,
> and this appears in the logs:
>
> messages:Oct 10 17:18:37 billmax /kernel: sio3 at port 0x2e8-0x2ef irq 9 on
> isa0 messages:Oct 10 17:18:38 billmax /kernel: sio3: type 16550A
> messages:Oct 10 17:20:16 billmax /kernel: sio3: 1 more silo overflow (total
> 1) messages:Oct 10 17:20:18 billmax /kernel: sio3: 1 more silo overflow
> (total 2) messages:Oct 10 17:20:21 billmax /kernel: sio3: 1 more silo
> overflow (total 3) messages:Oct 10 17:20:22 billmax /kernel: sio3: 1 more
> silo overflow (total 4) messages:Oct 10 17:20:23 billmax /kernel: sio3: 1
> more silo overflow (total 5) messages:Oct 10 17:20:27 billmax /kernel:
> sio3: 1 more silo overflow (total 6) messages:Oct 10 17:20:36 billmax
> /kernel: sio3: 1 more silo overflow (total 7) messages:Oct 10 17:20:38
> billmax /kernel: sio3: 1 more silo overflow (total 8) messages:Oct 10
> 17:20:45 billmax /kernel: sio3: 1 more silo overflow (total 9) messages:Oct
> 10 17:20:48 billmax /kernel: sio3: 1 more silo overflow (total 10)
> messages:Oct 10 17:21:04 billmax /kernel: sio3: 1 more silo overflow (total
> 11) messages:Oct 10 17:22:15 billmax /kernel: sio3: 1 more silo overflow
> (total 12) messages:Oct 10 17:40:07 billmax /kernel: sio3: 1 more silo
> overflow (total 13) messages:Oct 10 17:46:29 billmax /kernel: sio3: 1 more
> silo overflow (total 14)
>
>
> If I move the console cable from com4 to com1 on the server and keep the
> console cable in the same switch, then `tip com1`, it works fine. It's just
> the sio3 port that I'm having trouble with. Note that this machine only has
> sio1 and sio3.
>
> Here's my sio kernel config:
>
> # Serial (COM) ports
> device          sio0    at isa? port IO_COM1 flags 0x10 irq 4
> device          sio1    at isa? port IO_COM2 irq 3
> device          sio2    at isa? disable port IO_COM3 irq 5
> device          sio3    at isa? port IO_COM4 flags 0x10 irq 9
>
> Also, I've tried it with AND without the 0x10 flag (which I know just
> allows the com device to be used as a serial console). AND I've tried it
> with the "do not use FIFO" flag (0x00002) on COM4, like this:
>
> # Serial (COM) ports
> device          sio0    at isa? port IO_COM1 flags 0x10 irq 4
> device          sio1    at isa? disable port IO_COM2 irq 3
> device          sio2    at isa? disable port IO_COM3 irq 5
> device          sio3    at isa? port IO_COM4 flags 0x00002 irq 9
>
>
>
> I get the same error in the log either way. Port speed is set to 9600 in
> all tests. I get the same problem under conserver, so it's not directly
> related to the `tip` command, but the device.
>
> Is there some magic voodoo flag that I need to pass to this port to get it
> working?
>

Dredging back through memory I seem to recall that irq 9 was somewhat
problematic (not specifically a FreeBSD problem) being a remapping of irq 2
which *sometimes* worked.

If possible it might be worth trying to rewire the interrupt to irq 3 or irq 
5.

But then difficulties of the past with irq 2/9 may have been solved in
modern hardware. On the other hand it seems to me that flakey interrupts
could give rise to the symptoms you are experiencing.

Malcolm