On Fri, 26 Sep 2003 08:43:33 -0700 (PDT) Bluesea Yreen <big_bluesea@yahoo.com> wrote: > It seems that setting "skb->ip_summed" to > "CHECKSUM_HW" makes software do more. If a NIC can > verify TCP/UDP checksum as well as calculate IP > payload checksum, is it better to set "skb->ip_summed" > to "CHECKSUM_UNNECESSARY" instead of "CHECKSUM_HW" > even it can provide IP payload checksum? I don't think > the software need to know TCP/UDP checksum if it knows > the checksum is correct. Is it right? > Wrong, these NICs that indicate CHECKSUM_HW only calculate a 16-bit raw 2's complement sum of the entire packet data. Without adjusting this properly we cannot know if the checksum given by the chip is correct or not. CHECKSUM_HW is advantageous, in that it means that the card can support hw checksumming for protocols other than ipv4, in particular ipv6. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
