IGB_RXBUFFER_2048
((NET_SKB_PAD + IGB_TS_HDR_LEN + IGB_RXBUFFER_1536) > SKB_WITH_OVERHEAD(IGB_RXBUFFER_2048))
return IGB_RXBUFFER_2048;
buf_size = IGB_RXBUFFER_2048;
(SKB_WITH_OVERHEAD(PAGE_SIZE) - IGB_RXBUFFER_2048)