share IRQ of SMC PCI Ethernet Card(DEC 21041) + SCSI Host Adapter

share IRQ of SMC PCI Ethernet Card(DEC 21041) + SCSI Host Adapter

Post by Uli Saue » Fri, 23 May 1997 04:00:00



I' m runnig linux 2.030 on an old Intel Batman
Motherboard(82434LX Mercury/Neptune chipset) with the AMI BIOS 1.00.08AF1.
The Host Adapter driver is compiled with the kernel. The tulip driver for
the Ethernet Card is compiled as a module.
I experimented with an Adaptec 2940 as well as with a Buslogic Bt946c
getting the same results on two different motherboards.
Both of the drivers always use the same IRQ, even if I mark more than one
IRQ as free (not used by ISA) in the PCI BIOS setup. So it seems that I
cannot prevent the drivers from using shared IRQ's.
At least in the doc of "drivers/scsi/BusLogic.c" and "drivers/pci/tulip.c"
I found hints that shared IRQ's are supported. So linux boots and works
without problems(my system disk is SCSI). The SCSI host adapter has even
no problems when I start the "tulip" module for the ethernet card. But
everytime I try to "ifconfig eth1 ..." I get the answer "SIOCSIFFLAGS: try
again".
netstat -i shows
Kernel Interface table
Iface   MTU Met  RX-OK RX-ERR RX-DRP RX-OVR  TX-OK TX-ERR TX-DRP TX-OVR
Flags
lo     3584   0     13      0      0      0     13      0      0      0
BLRU
dummy  1500   0      0      0      0      0      0      0      0      0
BORU
eth0   1500   0 120791      0      0      0 223570      0      0      0
BRU
eth0 is another ne2000 ISA Ethernet Card running without problems.
Nevertheless I may setup routes and networks for eth1 without getting
failures. But no connection is possible.
All of the cards work fine if alone on the bus.
I experimented with an Adaptec 2940 as well as with a Buslogic Bt946c
getting the same results on two different motherboards. Besides the
mentioned Intel Batman I used a modern Chaintech Board with an Award Bios.
Here Both of the Cards work together if they are led to use different
IRQ's. But if urge them to use shared IRQ's by marking only one IRQ as
free for PCI Bus then they show the same behaviour as in the INTEL Batman
Board.
Here is what "cat /proc/pci" tells on the problematic Batman Board:
PCI devices found:
  Bus  0, device  14, function  0:
    SCSI storage controller: Adaptec AIC-7871 (rev 0).
      Medium devsel.  Fast back-to-back capable.  IRQ 11.  Master Capable.
Latency=64.  Min Gnt=8.Max Lat=8.
      I/O at 0xf800.
      Non-prefetchable 32 bit memory at 0xffbef000.
  Bus  0, device   6, function  0:
    Ethernet controller: DEC DC21041 (rev 17).
      Medium devsel.  Fast back-to-back capable.  IRQ 11.  Master Capable.
Latency=64.  
      I/O at 0xfc80.
      Non-prefetchable 32 bit memory at 0xffbfff80.
  Bus  0, device   2, function  0:
    Non-VGA device: Intel 82378IB (rev 0).
      Medium devsel.  Master Capable.  No bursts.  
  Bus  0, device   0, function  0:
    Host bridge: Intel 82434LX Mercury/Neptune (rev 3).
      Slow devsel.  Master Capable.  Latency=64.  

Thanks in advance for reading and much more thanks for giving me a hint.

Ulrich Sauer
Universitaet Osnabrueck
Institut fuer semantische Informationsverarbeitung
Tel. 0541 969 2584