Re: linux 2.1.5[45] and PCI bus

Thorsten Kukuk (kukuk@weber.uni-paderborn.de)
Sat, 13 Sep 1997 13:38:45 +0200 (MET DST)

> > since linux 2.1.54, the kernel will not found the PCI bus anymore.
> > I have enabled:
> > CONFIG_PCI=y
> > CONFIG_PCI_BIOS=y
> > CONFIG_PCI_DIRECT=y
> > CONFIG_PCI_OPTIMIZE=y
> >
> > The boot message is:
> > PCI: No PCI bus found.
> >
> > I use binutils 2.8.1.0.15, gcc 2.7.2.3, glibc 2.0.5.
> > The hardware is:
> > Tyan Tomcat III (Bios 4.01) with 2 133Mhz Pentium prozessors,
> > and NCR 875 SCSI Controller.
> >
> > Any Ideas ?
>
> For recent hardwares CONFIG_PCI_OPTIMIZE may break the host bridge
> settings, since it does not seem to probe accurately the bridge type.
> In fact the CONFIG_PCI_OPTIMIZE option is a very old hack that
> have'nt been maintained and should have been removed from the kernel
> since years.

This was it. When disabling CONFIG_PCI_OPTIMIZE, I have no problems with
the PCI bus.

CONFIG_PCI=y
CONFIG_PCI_BIOS=y
CONFIG_PCI_DIRECT=n

and

CONFIG_PCI=y
CONFIG_PCI_BIOS=n
CONFIG_PCI_DIRECT=y

will both work.

We should change the Help text for CONFIG_PCI_OPTIMIZE:
from linux/Documentation/Configure.help:

PCI bridge optimization (experimental)
CONFIG_PCI_OPTIMIZE
This can improve access times for some hardware devices under
certain BIOSes if your computer uses a PCI bus system. This is
recommended; say Y.

Between, the TYAN Tomcat III uses the Intel 430HX Chipset.

Thanks for all the help,

Thorsten

-- 
Thorsten Kukuk  kukuk@vt.uni-paderborn.de
                http://www-vt.uni-paderborn.de/~kukuk/
Linux is like a Vorlon.  It is incredibly powerful, gives terse,
cryptic answers and has a lot of things going on in the background.