Hi,
I currently think that this patch is wrong and should be reverted.
It fixes a certain use case by hacking the PCI device id, but does
not model the way how that device id is set on the real hardware
correctly.
As far as I know, all i82559 have a default PCI device id of 0x1229.
It can be changed by the EEPROM configuration, but not all network
cards do have an EEPROM.
See for example this URL for more information:
http://zoo.cs.yale.edu/classes/cs422/2010/ref/82559_eeprom.pdf
The correct solution is modeling the EEPROM and allowing QEMU
users to provide an EEPROM file.