Cyclone 3x905b Corruption/problems

Donald Becker
Thu Mar 18 11:46:09 1999

On Thu, 18 Mar 1999, Michael Thompson wrote:

> I have a DEC 486-66 box running redhat 5.2 with a 2.2.3 kernel.  The box
> but any attempts to download large files (be it HTTP, FTP, samba, etc)
> lead to corruption.  It normally crops up in large files (20+ meg)
> but corrupts smaller ones randomly.  Zip files pop up with CRC errors,
> Mar 17 19:05:28 server kernel: CPU0: Intel 486 DX/2 stepping 05
> Mar 17 19:05:28 server kernel: eth1: 3Com 3c905B Cyclone 100baseTx at
> 0xd200,  0

You have a 486 PCI chipset with bugs in burst mode.

One work-around is to limit or disable burst mode, but that results in bad
performance.  Sometimes an updated BIOS that sets the PCI CacheLineSize
register on the card to a small value avoids the problem.  Another
work-around is to avoid using bus-master PCI devices, e.g. use a $10 PCI
NE2000 clone.

The Tulip chips have a burst limit setting that allows working around this
bug, but most other adapter chips do not.

The real solution is to get a non-broken motherboard.

Donald Becker
USRA-CESDIS, Center of Excellence in Space Data and Information Sciences.
Code 930.5, Goddard Space Flight Center,  Greenbelt, MD.  20771