igb mtu change

igb_change_mtu change is only changing adapter->rx_ring[0]->rx_buffer_len.

1)  we dont have to change adapter->tx_ring[0]->rx_buffer_len ?
2) Is there any way to set different values to
adapter->tx_ring[0]->rx_buffer_len and
adapter->rx_ring[0]->rx_buffer_len ?

I am facing a problem because i have a strange requirement....i have
2KB  bufffer pools ( GFP_DMA ) in kernel.
When i receive a jumbo pkt of size 9126,     five rx_desc should be
used to recieve paket. So the first rx_desc will have a status error
bit indicating that it is not
EOP ( eop ) ....I could easily keep track of my 2KB buffer pools.

But when sending ...i wll collect all  2KB buffers of same jumbo frame
and dma to tx_ring....
So i need  1500  on rx_ring[0]->rx_buffer_len and  9126 on
adapter->tx_ring[0]->rx_buffer_len. .Is there any way ?

Thanks,
Ratheesh