Date: Thu, 28 Oct 1999 18:03:20 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-current@FreeBSD.ORG Subject: Re: odd NFS behaviour with DU 4.F client Message-ID: <199910290103.SAA13818@apollo.backplane.com> References: <14360.50663.727201.679421@grasshopper.cs.duke.edu> <199910282225.PAA12530@apollo.backplane.com> <14360.60247.329457.247327@grasshopper.cs.duke.edu>
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:Speaking of NFS changes, there was talk at one time about turning the
:nfsm macros into functions. Is this going to happen?
No. The nfsm macros have goto's all over the place that jump outside
the macro, and also use local variables declared outside the macro.
Short of rewriting a fairly large hunk of the NFS code entirely it
aint gonna happen. Nobody is contemplating rewriting the code.
:I ask because I've seen occasional unaligned access panics on
:FreeBSD/alpha in the client side code. I've only seen them on a
:really lossy link (basically a misconfigured duplex on a 100Mb link).
:They tend to be in nfs_request (nfs/nfs_socket.c:110) or nfs_readrpc
:(nfs/nfs_vnops.c:1093). These are both calls to nfs macros that would
:be a lot easier to debug if they weren't macros ;-)
:
:Thanks,
:
:Drew
:------------------------------------------------------------------------------
:Andrew Gallatin, Sr Systems Programmer http://www.cs.duke.edu/~gallatin
You can use gdb to disassemble the code to locate the exact point where
the panic occured. It is definitely more difficult, but there isn't
much we can do about it. The rpc design tends to keep things aligned
and NFS packet elements tend to be sized such that alignment remains
intact, so if these panics can be tracked down the fixes should be
relatively easy to make. Unfortunately, we just don't see these sorts
of panics on Intel boxes all that much because IA32 allows misaligned
accesses. This means there are almost certainly alignment bugs in the
code.
-Matt
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