The Virtex-4 MGT does not channel bond? Why is this the case?
One reason channel bonding will not work concerns how the CHAN_BOND_SEQ_x_MASK and the CHAN_BOND_SEQ_LEN are set. CHAN_BOND_SEQ_x_MASK and CHAN_BOND_SEQ_LEN have to match up; otherwise, channel bonding will not occur.
For example, if the channel bond sequence is a single byte symbol:
CHANNEL BOND WORKING EXAMPLE
CHAN_BOND_SEQ_x_MASK => "1011" -- Only single byte mask. Note single byte does not have to be in fixed position as long as it is only single byte
CHAN_BOND_SEQ_LEN => 1
CHANNEL BOND NOT WORKING EXAMPLE
CHAN_BOND_SEQ_x_MASK => "0000" -- Multiple byte mask when sequence length is only 1.
CHAN_BOND_SEQ_LEN => 1