On Tue, Jan 30, 2007 at 11:15:20AM -0800, Stephen Hemminger wrote:
> a) hardware flow control problems
> look at ethtool -S eth0 statistics, are there flow control packets
> showing up?
on yeti (machine from which i quoted the first log
output),
[EMAIL PROTECTED] /root]# /root/ethtool -S eth0 | grep mac_pause
tx_mac_pause: 0
rx_mac_pause: 8649
and on t1 both 0.
But presumably you want to know this at the point of the
failure -- I'll add it to the things the watchdog records
before rebooting.
> b) GMAC or ram buffer issues
> looking at 'ethtool -d eth0' output can help, but it is a needle in
> haystack finding these setup errors.
>
> The sky2 driver copies most of the stuff from vendor version of sk98lin,
> but if sk98lin works and sky2 doesn't then comparing register settings
> can give hints.
ok. I'll try to get one of these machines running the
vendor driver to see whether the problems still occur.
> c) DMA problems
> For some problems, I have had luck adding a /proc interface and dumping
> the transmit ring after a hang. Looking at the last control block that
> hung can help. This found the case where IPV6 TSO was leaking through.
>
> d) checksum problems
> Turning off tx scatter/gather forces non fragmented skb's. This hurts
> performance, but can tell if the problem is with fragment code.
> Turning off tx checksum turns off scatter/gather, checksumming and
> TSO.
also seems worth trying, though without a test case it'll
take a while to be sure what was causing the problem.
> e) possible alignment and flow control interaction
> Because the receive DMA engine has hardware bugs and requires alignment
> or it doesn't work with flow control. I still wonder if there are alignment
> bugs on Tx with flow control.
>
> f) other driver bug
>
> To save time, I'll go get a new Mac Mini and try and clone this setup.
> Could you send me a full kernel config (and other setup information
> like filesystem type, distro etc).
we've seen this on lots of different machines; yeti is
NFS-root, originally ancient Redhat plus lots of
locally-built packages with some bits of the filesystem on
ext3. t1 is Ubuntu (`edgy' I think) on ext3. The same
problems occur on Debian `sarge' and CentOS, though.
What I haven't yet managed to do is to reproduce the
problem -- the test machine on my desk (also NFS-root)
has never exhibited it. But it's mostly idle.
[...]
> The vendor driver does some slightly different setup, but it also
> does a hardware reset when inactive (every 10ms).
!!!
--
``I have a sneaking sympathy for Belgium, as a land where, by accident of
geography, too often other people have chosen to hold their wars.''
(Alan Follett)
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