Ethtool Shows Unknown Speed and Duplex (16563881)

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When ethtool command is used on Oracle VM 3.3.2 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