Broadcom Support

[NiKiZe]

Indeed 14e4:1639 does not have any native driver in iPXE

how do you then start ipxe.iso?
if you can chainload over the network instead then you can use undionly.kpxe which will use the existing NIC ROMs UNDI stack to do communication instead.
or if you want EFI use snponly.efi or ipxe.efi and it might work via the SNP/NII driver mode instead (using the firmware driver for the NIC)

If this does not help you then you could add appropriate PCI_ROM line in the bnx2.c file, but might be several things missing in there to have it working right of the bat.
Let us know how it goes.