Bug#404447: nfs-kernel-server: Transferred files get corrupted

[Martin Michlmayr <tbm@cyrius.com>]

retitle 404447 ixp4xx: open source network driver behavingly badly under load, can cause corruption
severity 404447 important
thanks

Hi Ahmad,

I've tested various combinations now and I'm pretty sure this is a
problem with the open source Ethernet driver for the IXP4xx platform.
I've tested:

 - NFS on another ARM platform, namely IOP32x: it works fine.

 - 2.6.18-2 on NSLU2 to rule out the mm/msync patches: it works fine.

 - 2.6.17 on NSLU2 using the Intel Ethernet driver: it works fine.

In 2.6.18 we have switched to a different Ethernet driver.  Various
people have experienced problems when transferring large amounts of
data with this driver, and given my tests I'm pretty sure that this is
what we're seeing in this case too.  Some people have suggested that
setting

    sysctl net.ipv4.tcp_wmem="4096 8092 8092"

helps.  Unfortunately, I still see NFS problems so it doesn't
completely get rid of the problems.

The bottom line is that this is a known bug in the Ethernet driver.
I'll ask the author of that driver whether he looked into these
problems already.  I hope this can be resolved in time for etch but
I'm not sure this will really happen.  In any case, I'm downgrading
this bug because Debian itself doesn't include the microcode needed
for IXP4xx Ethernet, so this isn't a release critical bug for Debian.
However, I still hope we can find a solution.
-- 
Martin Michlmayr
http://www.cyrius.com/