Date: Tue, 25 Apr 2000 17:03:57 -0700 (PDT) From: Archie Cobbs <archie@whistle.com> To: csg@waterspout.com (C. Stephen Gunn) Cc: freebsd-net@freebsd.org Subject: Re: Proposal for ethernet, bridging, netgraph Message-ID: <200004260003.RAA55104@bubba.whistle.com> In-Reply-To: <20000425164027.A2553@waterspout.com> from "C. Stephen Gunn" at "Apr 25, 2000 04:40:27 pm"
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C. Stephen Gunn writes: > > 2. NFS requires that the IP packet be longword aligned (or something). > > If you start the mbuf with a 14-byte Ethernet header, then this > > is broken (?? is this still true ??) > > Perhaps I misunderstand something here, but the packet-header should > be long-since-gone by the time it gets to NFS. If NFS needs the > packet aligned, I'd assume that NFS takes care that monkey-business. Well, the mbuf is aligned.. so if the IP header starts at mbuf + 14, then it's not aligned... and m_adj() won't help either.. but I don't know whether this is still valid though. However, a couple of drivers take pains to handle this. > > 3. Some code actually reads the header and the payload into > > different buffers. Putting them together, and then separating > > them again later would be slower than it is now. > > I did a quick sampling of Ethernet devices in the kernel, and I > couldn't find any that didn't call m_adj() right before ether_input(). > This was back in January, so I can't be sure now it was an exhaustive > search. See dev/ie/if_ie.c for an example.. -Archie ___________________________________________________________________________ Archie Cobbs * Whistle Communications, Inc. * http://www.whistle.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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