On Mon, 24 Dec 2007 19:45:23 +0000 Al Viro <[EMAIL PROTECTED]> wrote:
> On Mon, Dec 24, 2007 at 11:36:38AM -0800, Stephen Hemminger wrote: > > > you will get the same behaviour on big- and little-endian boxen, even > > > though > > > the intermediate integer values will be of course different. > > > > > > skb->csum *must* be stored in the same order on l-e and b-e boxen; that > > > way you don't need to convert it or raw data when updating the sucker [*]. > > > > > > [*] it's slightly more complicated since skb->csum is 4-byte, not 2-byte > > > and the real invariant is "checksum of 4-octet array at &skb->csum must > > > not depend on host" (so e.g XX YY 00 00 and 00 00 XX YY are equivalent - > > > checksum doesn't change from reordering octet pairs; XX YY 00 00 and > > > 00 00 YY XX are very definitely *NOT* equivalent; odd and even bytes > > > can't be exchanged). > > > > Did you test this on real hardware? > > Test _what_ on real hardware? That kernel expects skb->csum fixed-endian? > That csum_add() and friends work? Yes to both. > > If you are asking whether I'd tested what skge does to csum in its rx > descriptors when asked to byteswap - as I've said, all skge-handled stuff > I have is on-board in little-endian boxen. Thus asking for folks who > could test it on big-endian and see what does that sucker actually do... I'll wait for 2.6.25 then. I am just concerned about how real hardware interprets the byte swap PCI flag. I'll see if I can find some cost competitive bigendian hardware. -- Stephen Hemminger <[EMAIL PROTECTED]> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
