There is a widespread problem with the Linux driver for the Realtek 8168/8169 cards where the modules load properly and the card is visible but no link is detected. E.g.:
Jun 21 18:28:41 localhost kernel: r8169: eth0: link down
Jun 21 18:28:41 localhost kernel: ADDRCONF(NETDEV_UP): eth0: link is not ready
There are lots of details and suggested solutions from the Ubuntu people. None of the suggestions worked for me, however. Several of them suggest configuring the card under Windows, but the box containing this device is a single-boot linux fileserver. The “wake-on-LAN” functionality seems to be implicated, but not in a way I can see how to fix.
After much head-banging (in the bad sense), I found a simple solution:
(1) Install ethtool
(2) Modify /etc/network/interfaces as follows (substitute your r8169 interface for ‘eth1′ and other settings accordingly):
iface eth1 inet static
pre-up /usr/sbin/ethtool -s eth1 autoneg off
This did the trick for me where no other solution would work. Of course, link autodetection no longer occurs, but that’s a small price to pay for connectivity.
This is a Debian etch installation using a slightly more recent kernel (2.6.25-2-686).
As an interesting side note, on this new box, the interface appears as eth0 in the kernel logs, but is actually mapped as eth1. Similarly, a second Ethernet interface appears in the log as a different device number than that by which it is referenced. Any ideas why?
Update 6/22/08: Still not getting 1000BaseT (Gigabit), however. If I force 1000BaseT with ethtool -s eth1 speed 1000, the link goes down again (even with autoneg off). The same card in another box, however, detects the link and goes to 1000BaseT automatically. So I’m stuck at 100BaseT.
Update 6/24/08: Linux 2.6.26-rc5 fixes the problem 100% for me.
[Tags]realtek, r8169, linux, drivers, hacking[/Tags]