silo overflow errors on sio/puc for SIIG PCI-4S

J. Seth Henry jshamlet at
Tue May 6 21:01:41 PDT 2003

I recently built a new home automation controller for my condo, using the
Eden EPIA board with the 933MHz processor (the Falcon CR51 to be specific,
but it's pretty much a case, PSU and mainboard)

I also installed a SIIG low-profile PCI-4S multi-port serial card
(LP-P40011) to handle the control portion. Everything works great - I've
already migrated all of the control software over to the new machine, but
I am getting a *LOT* of silo errors in the syslog.

Even 2400 baud (the SmartUPS) is resulting in these. Since this is a
control system, I am getting hundreds of messages. I've managed to reduce
this a bit by putting the thermostat, and a CM17A (bottlerocket), on the
built-in COM port - but the UPS and CM11A are still generating a large
number of messages.

I did read in the puc manpage that if you get these, add in the option for
fast interrupts. I did this, and am still getting the silo errors. It also
mentioned that PCI interrupt sharing would be a problem - but nothing
appears to be sharing that interrupt (irq 12) - at least in the dmesg.

Now, this machine is no speed demon, but it should be fast enough to
handle a PCI serial card. Integer speed is fairly quick, and it can even
handle xdm with no problems.

Just for giggles, here is the dmesg output for the system:
Copyright (c) 1992-2003 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 4.8-RELEASE #2: Tue May  6 20:10:46 EDT 2003
    root at
Timecounter "i8254"  frequency 1193182 Hz
Timecounter "TSC"  frequency 933371430 Hz
CPU: VIA C3 Samuel 2 (933.37-MHz 686-class CPU)
  Origin = "CentaurHauls"  Id = 0x67a  Stepping = 10
real memory  = 132055040 (128960K bytes)
avail memory = 125128704 (122196K bytes)
Preloaded elf kernel "kernel" at 0xc0357000.
md0: Malloc disk
Using $PIR table, 5 entries at 0xc00fdc80
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Host to PCI bridge> on motherboard
pci0: <PCI bus> on pcib0
pcib1: <PCI to PCI bridge (vendor=1106 device=8601)> at device 1.0 on pci0
pci1: <PCI bus> on pcib1
pci1: <Trident model 8500 VGA-compatible display device> at 0.0 irq 11
isab0: <PCI to ISA bridge (vendor=1106 device=8231)> at device 17.0 on
isa0: <ISA bus> on isab0
atapci0: <VIA 8231 ATA100 controller> port 0xc000-0xc00f at device 17.1 on
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
uhci0: <VIA 83C572 USB controller> port 0xc400-0xc41f irq 3 at device 17.2
on pci0
usb0: <VIA 83C572 USB controller> on uhci0
usb0: USB revision 1.0
uhub0: VIA UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
uhci1: <VIA 83C572 USB controller> port 0xc800-0xc81f irq 3 at device 17.3
on pci0
usb1: <VIA 83C572 USB controller> on uhci1
usb1: USB revision 1.0
uhub1: VIA UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub1: 2 ports with 2 removable, self powered
chip1: <PCI to Other bridge (vendor=1106 device=8235)> at device 17.4 on
pcm0: <VIA VT82C686A> port 0xd400-0xd403,0xd000-0xd003,0xcc00-0xccff irq
10 at device 17.5 on pci0
pcm0: <unknown ac97 codec> (id=0x56494161)
vr0: <VIA VT6102 Rhine II 10/100BaseTX> port 0xd800-0xd8ff mem
0xe3000000-0xe30000ff irq 11 at device 18.0 on pci0
vr0: Ethernet address: 00:40:63:c2:5f:e9
miibus0: <MII bus> on vr0
ukphy0: <Generic IEEE 802.3u media interface> on miibus0
ukphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
puc0: <SIIG Cyber 4S PCI 16C550 (20x family)> port
0xe800-0xe807,0xe400-0xe407,0xe000-0xe007,0xdc00-0xdc07 irq 12 at device 2
0.0 on pci0
sio1: type 16550A
sio2: type 16550A
sio3: type 16550A
sio4: type 16550A
orm0: <Option ROMs> at iomem
0xc0000-0xcbfff,0xcc000-0xcffff,0xd0000-0xd97ff on isa0
atkbdc0: <Keyboard controller (i8042)> at port 0x60,0x64 on isa0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
kbd0 at atkbd0
vga0: <Generic ISA VGA> at port 0x3c0-0x3df iomem 0xa0000-0xbffff on isa0
sc0: <System console> at flags 0x100 on isa0
sc0: VGA <16 virtual consoles, flags=0x300>
sio0 at port 0x3f8-0x3ff irq 4 on isa0
sio0: type 16550A
ppc0: <Parallel port> at port 0x378-0x37f irq 7 on isa0
ppc0: Generic chipset (EPP/NIBBLE) in COMPATIBLE mode
plip0: <PLIP network interface> on ppbus0
lpt0: <Printer> on ppbus0
lpt0: Interrupt-driven port
ppi0: <Parallel I/O> on ppbus0
joy0 at port 0x201 on isa0
ad0: 9590MB <IBM-DJSA-210> [19485/16/63] at ata0-master UDMA66
acd0: CDROM <CDU5211> at ata1-master PIO4
Mounting root from ufs:/dev/ad0s1a
sio3: 1 more silo overflow (total 1)
sio3: 1 more silo overflow (total 2)
sio3: 1 more silo overflow (total 3)
sio3: 1 more silo overflow (total 4)
sio3: 1 more silo overflow (total 5)
sio3: 1 more silo overflow (total 6)
sio2: 1 more silo overflow (total 1)
sio3: 1 more silo overflow (total 7)
sio2: 1 more silo overflow (total 2)
sio2: 1 more silo overflow (total 3)

Note: COM2 on this board is a FIR/CIR header - which I don't have the
matching hardware for - so it is disabled in this kernel config.

Am I stuck, or is there anything I can do to resolve this?

Seth Henry

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