When the embedded design contains two ethernet cores, Libgen is copying xemac_g.c from the C:\edk\sw\ThirdParty\bsp\linux_mvl31_v1_01_a\drivers\emac_v1_00_e\src directory. This results in the wrong xemac_g.c being included with the MontaVista Linux Kernel. The xemac_g.c file should be copied from the ppc405_i\libsrc\emac_v1_00_e\src directory.
This problem has been fixed in the latest EDK 8.1i Service Pack, available at:
The first service pack containing the fix is EDK 8.1i Service Pack 2.