When ethtool command is used on Oracle VM server, the status "Unknown!" is displayed for the Speed and Duplex settings. For example:
# ethtool eth0
Settings for eth0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric
Advertised auto-negotiation: Yes
Speed: Unknown!
Duplex: Unknown! (255)
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000007 (7)
Link detected: no
The problem is due to insufficient interrupt resources available to report the appropriate status.
Workaround
Edit the grub.conf file to add the following kernel boot parameters:
extra_guest_irqs=64,2048 nr_irqs=2048