Re: Unable to handle kernel NULL pointer... on cat /proc/pci

Magnus Sjoegren (
Wed, 24 Sep 1997 14:45:26 +0200 (MET DST)

On Wed, 24 Sep 1997, Gabriel Paubert wrote:

> Functions are numbered 0 to 7, and you might overflow the buffer
> when doing cat /proc/pci. But it also might be that your chipset
> returns 0xffffffff when the device field is invalid (can not select the
> IDSEL pin of any device) and 0xEFFFFFFF when it starts a configuration
> cycle that is terminated by a master abort (when a device might be
> connected).

Ok, I don't know if this is any help but I am adding additional info.

The unknown pci device warning message at bootup sometimes display
Warning : Unknown PCI device (eeff:ffff). Please read include/linux/pci.h
instead of ^
Warning : Unknown PCI device (efff:ffff). Please read include/linux/pci.h

> Note that I don't think that my patch is the right thing to do, it was
> written to verify where the problem was.
> But the problem to avoid detecting a spurious device with broken hardware
> is much more complex. The idea I have now is to try to clear all the error
> bits from the PCI_STATUS register and to check that they are
> effectively cleared, this should also make your /proc/pci less cluttered.

In simpler words, this will reduce the warning messages at bootup and
simultaneously reduce the input of unknown devices in /proc/pci?

As it is now I can only see unknown devices when viewing /proc/pci.

> My opinion is that clearing these bits during bus scan at boot is harmless
> and is a reliable indication of the presence of a device.
> Comments, flames ?

Im willing to give it a try.