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SubjectRe: cat /proc/pci and NCR 810 SCSI parity error

On Wed, 7 Oct 1998, Harald Koenig wrote:

> using 2.1.122 with CONFIG_PCI_OLD_PROC=y I get a SCSI parity error
> when running
> # od -tx1 -Ax /proc/bus/pci/00/01.0
> # cat /proc/pci
> where /proc/bus/pci/00/01.0 is the NCR810 (kernel messages below)
> any idea what's wrong with accessing /proc/bus/pci/00/01.0 and `cat /proc/pci'
> and/or 2.1.122 ?

I have the same effect when doing the same operation on a 53C825A.
However it only occurs when typing the od command from a root account. So
it's a non issue (only root can provoke it and it does not seem to do any
harm), it might even be (highly speculative, I don't have the docs) that a
feature of the chip is the ability to inject artificial parity errors for
testing, although it would be weird to do it from read access of the
configuration space.

Note that typing lspci -xx whill have exactly the same effect as od, only
that not everybody making the transition from 2.0.xx to 2.1.xx has
downloaded pciutils.

Some Intel chipsets lockup when reading the whole configuration space
AFAIR: using od or lspci -xx on /proc/bus/pci/... is not always safe from
a root account. From non root accounts, you can only read the first 64
bytes of config space, which has been safe on all devices until now, but
cannot even been guaranteed in the future given the general tendency to
violate PCI specs in new and innovative ways :-) These violations are
often due to little known companies like Intel, Compaq, S3, etc... who
carefully target their R&D resources to keep up with their reputation for
being innovative :-)


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