Matthew Dillon writes:
>:Thanks, but there is code in rl_rxeof() to align to a 32 bit boundary.
>:If that weren't the case than I would expect the Alpha to panic with
>:other IP applications, not just NFS.
>:I don't know, NFS must be doing something weird.
>    NFS will realign the data payload for misaligned packets.
>    I agree it sounds like an issue in the NFS code somewhere.  Something
>    that is slipping through unnoticed.  If someone can get a crash dump
>    and do a stack backtrace, or even a simple DDB 'trace', it should be 
>    opssible to track the problem down.

OK. Unfortunately, gdb core dumps when I try to analyze a crash dump
with a debugging kernel :( Even worse, gdb core dumps when I try to
run a debugging gdb in gdb to find out why gdb is core dumping when
I try to debug a kernel with symbols :(( Wonderful.

I've managed to produce 5 crash dumps so far. Trace in ddb shows that
the kernel is panicing in various places, so Matt's thesis that it will
be easy to pinpoint is apparently shot full of holes :(

I've tried various combinations of nfs mounting with tcp, nfsv2, nfsv3,
w=1024 and r=1024. Using TCP mounts makes the panic happen less quickly,
but as soon as I `ls' a "big" directory the kernel panics. "Big" seems to
be more than 10 or 15 entries.

Anyway, here's some of the output from a trace in ddb:

panic() at panic+0x100
trap() at trap+0x610
XentUna() at XentUna+0x200
[here a list of various locations in the nfs code from various panics]
nfs_readdirrpc() at nfs_readdirrpc+0x10ec
nfs_readdirrpc() at nfs_readdirrpc+0x12bc
nfs_request() at nfs_request+0x79c
nfs3_access_otw() at nfs3_access_otw+0x744
nfs_lookup() at [I didn't write down the offset]

Looking at a disassembly of e.g. nfs_readdirrpc tells me nothing at all.
The Alpha's assembly is highly non-transparent. Trying to figure where
the corresponding line in the C-code is located is pretty much impossible
without debugging symbols - but see above.

Looks like I'll have to live without NFS. At least cvsup works so I can
keep my src and ports up to date.

BTW I'm not using any off-the-wall options to compile the kernel. Just
-O -pipe.


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