PING: Someone on the core team. (Modem Problem)

[Daniel Rudy]

At about the time of 2/15/2007 12:14 AM, Peter Jeremy stated the following:
> On 2007-Feb-14 00:27:36 -0800, Daniel Rudy <dr2867 at pacbell.net> wrote:
>> Changing the slot did help.  I moved it from slot 3 to slot 1.  But, now
>> it's dropping characters with a port speed of 57600, and I am also
>> getting irq overrun errors from the kernel too now.
> 
> This is not good.  Interrupt latency is a bit of a sore point but the
> FIFO trigger level is 8 bytes so getting SILO overflows implies a
> latency of >1.38msec.  Does sio4 report as [FAST] in the dmesg?

No, it does not report as fast.  I changed the /boot/device.hints file
and commented out all the sio devices, since all the serial ports on the
system are disabled anyways.  This is the only one that is up and running.

Here is the verbose dmesg from a reboot that I did just now:

sio0: Reserved 0x100 bytes for rid 0x14 type 4 at 0xd400
sio0: configured irq 17 not in bitmap of probed irqs 0
sio0: port may not be enabled
sio0: irq maps: 0xcb9 0xcb9 0xcb9 0xcb9
sio0: <Lucent kermit based PCI Modem> port
0xd400-0xd4ff,0xd800-0xd8ff,0xdc00-0xdc07 mem 0xeb105000-0xeb1050ff
 irq 17 at device 9.0 on pci0
sio0: type 16550A

What I don't understand is why it keeps saying that "configured irq 17
not in bitmap of probed irqs 0"...  What exactly does that mean?

> Unfortunately, there's no easy way to change the FIFO trigger level -
> you would need to patch the source code (look for FIFO_RX_MEDH in
> /usr/sys/dev/sio/sio.c if you want to go down this path).
> 
>>  With a port speed of 2400, I do not drop characters.
> 
> The FIFO is not enabled at speeds at or below 4800bps.
> 

I'll try playing with that #define and see how that works then.  I don;t
think I can break it anymore than it already is.

-- 
Daniel Rudy