On Mon, Sep 15, 2003 at 04:05:52PM +0300, Shmulik Hen wrote: > > > NETIF_F_FRAGLIST <------------------- ??? WHAT IS THIS ??? > > Scatter/gather IO. > > That's for adapters that can follow a chain of skb's as well as scan > through the array of fragments in each skb (which is limited by > MAX_SKB_FRAGS). Not sure which level of the stack actually uses that > feature, but it may be usefull for passing a list of skb's, all > belonging to a single "packet". > Af far as I was able to find-out by chaching pointers in the kernel sources, "frag_list"s seem to be only used for upsteam packets (received packets). Furthermore the only devices specifying the NETIF_F_FRAGLIST feature are the loopback device and ieee1394. Both of them don't seem to use the "frag_list"s that much! Elsewhere (in a mailing list) I saw mentioned that frag-lists are used when the maximum number of fragments in an skb is not enough for a packet, so a second "skb" is allocated of which only "skb_shared_info" is actually used to keep the extra fragments (not "skb->base"). This sounds a bit strange, though (why waste a whole "skb" just to keep a few extra fragment descriptors)! Does anybody know what's the case with "frag_list"s? /npat -- When it is incorrect, it is, at least *authoritatively* incorrect -- Douglas Adams, The Hitchhiker's Guide to the Galaxy - : 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
