Re: PCI bridge optimization

=?ISO-8859-1?Q?Stefan_R=F6hrich?= (
Sun, 29 Sep 1996 16:57:05 +0200 (MET DST)


On Fri, 27 Sep 1996, Jon Lewis wrote:

> On a warm reboot, its SCSI disk was not detected. I hit the reset switch
> again, and again it started to boot and the SDMS info displayed, but no
> disk was detected. After turning the system off, waiting a few seconds,
> and turning it back on, all was well.
> The system is a 1.5 year old AIR dual P90 (only 1 CPU installed) with
> AIC-7870 (turned off) built into the board and NCR 810 (using NCR53C8XX
> driver) controlling a Micropolis 3243 and AHA-1540 controlling a Conner
> DAT.

I have the same problem with the warm reboot. But I think, it's caused by
the Adaptec SCSI controller, because this happens even if I turn off PCI
bridge optimizations.

I'm using an Adaptec 2940AU controller (I had to patch the kernel to
recognize the AIC-7861 chip) and if I try a warm reboot, the Adaptec
doesn't detect any device, but displays a timeout error (so that's a
different message than if I only disconnect all SCSI devices).

If I then continue the boot process with a boot floppy (I can't warm boot
from hard disk, because I've no IDE disks and the SCSI disk isn't
recognized at the warm reboot), the kernel hangs during initializing the
Adaptec SCSI controller driver. If I turn the power off before booting (on
all attached (even external) SCSI devices, too), everything works well,
except that a hard disk which should be an ultra scsi device according to
the web site of the manufacturer, is only recognized at 10 MHz
synchronous, not 20 MHz. Everything works well with Windows NT, but there
I didn't find any possibility to show, if the disk is treated as an ultra

There are some more strange things, e.g. at the warm reboot the SCSI
devices aren't detected and displayed, but if I go into the Adaptec bios
setup they show up in the hard disk tools (or similar) list.

Another curious thing is, that even with pci bridge optimization turned
on, no message like:
PCI bridge optimization.
Cache L2: Not supported.
CPU-PCI posted write: on.
CPU-Memory posted write: on.
PCI-Memory posted write: on.
PCI burst: on.
(as on my computer at home) is displayed, board is an Asus board with
Pentium 133, 82371SB Natoma/Triton II PIIX3 and 82437VX Triton II chips
(from /proc/pci) and an onboad IDE interface which is turned off.

I have heard from more people having this problem with the AIC 7861 chip,
maybe it's the same with the AIC-7870. I have this problem with any warm
reboot, but I've also heard that with some configurations it disappears
sometimes, but I don't know which configuration this was.

Does anybody else have this problem and/or a solution?

Maybe it's a problem with the pci interface of the Adaptec?


Stefan Röhrich