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Date: Sat, 8 Feb 1997 18:53:21 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199702080753.SAA04049@godzilla.zeta.org.au>
To: dk@genesyslab.com, freebsd-hackers@freebsd.org
Subject: Re: 2.2 panic in i586_bc1 call from nfs_writerpc()
Cc: dk@farm.org
Sender: owner-hackers@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

>there are 2 calls to bcopy() in nfs_vnops.c:nfs_writerpc(), but the logic 
>is that only one of them can be executed at one invocation.

Logic is that neither can have got to i586_bc1, since they only copy 8
bytes and i586_bc1 is only used for >= 1024 bytes :-).

>(btw, gdb cannot disassemble functions in support.s ;-(  but it's easy
                  ^^^^^^^^^^^ backtrace
>to see that it's within i586_bc1 anyway (next label is i586_global_bcopy,
>and that address is higher than fault's).

The frame pointer isn't set up for the functions in support.s, so the
backtrace probably skips one function: nfs_writerpc() called something
that called bcopy().

Do you use nfsv3?  v2 obviously won't work properly with files
larger than 2GB or 4GB.  E.g., for v2, nfs_writerpc() uses
txdr_unsigned(uiop->uio_offset) and throws away the high 32 bits of
the offset :-(.

Bruce