[vortex-bug] transfer errors with 3C905C-TX-M

[Donald Becker]

On Tue, 5 Sep 2000, Andrew Morton wrote:

> Donald Becker wrote:
> > 
> > You can disable this checksumming by changing line 1826 (approximately)
> > from
> >                 skb->ip_summed = CHECKSUM_UNNECESSARY;
> > to
> >                 skb->ip_summed = 0;
> > 
> > My guess is that you will still have data corruption.  If so, you have a
> > problem with your memory or disk controller.
> 
> Yup.  I've seen similar problems (different NIC) with bit flippage
> when the NIC was DMAing into main memory.
> 
> Software checksumming will fix this.  Hardware checksumming won't.

This should nominally be caught by PCI address and data parity checks, if
your motherboard has the hardware for bus parity checks.

Data corruption internal to the adapter or on the path to main memory was
one of the concerns about using hardware checksumming support.

(The other concern is verifying the correctness of partial checksum assist,
where the adapter provides a partial checksum and the driver corrects the
checksum for the header and CRC.)

I still believe that this problem is caused by bad main memory.

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Beowulf-II Cluster Distribution
Annapolis MD 21403