(fwd) Re: Can't run executables on NFS mounts!

["H. J. Lu" <hjl@freya.yggdrasil.com>]

Any ideas?

H.J.
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From: Richard Jones <rjones@orchestream.com>
Subject: Re: Can't run executables on NFS mounts!
Newsgroups: comp.os.linux.development.system,comp.os.linux.networking
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Mark Tranchant <mtranch2@> wrote:
> The subject sums it up quite well. I am on a large distributed network, 
> and Linux is "stowing away" on my work PC. I have tried to move some 
> of my filesystem onto a network file server, but have found that on 
> upgrading to a 2.1 kernel, I can't run executables from the NFS 
> mounts. If I try, the executable dies straight away with a segfault, 
> and dumps core.

> This is *really* annoying - can anyone help?

Yes, very obscure and very annoying bug. The problem
is to do with the blocksize of the NFS mounts, which in
2.1 defaults to something huge like 16k. This causes
problems with ld-linux.so when it tries to load a shared
library and it doesn't happen to align the library to
a 16k boundary (eg. it aligns it to 8k instead).

You can solve this in two ways: (a) force the NFS block
size in the kernel to something a little bit smaller (4K or 8K)
or (b) patch your loader to align the libraries to a
larger block size. I think you can either achieve (a)
by mounting with rsize=wsize=4096 and if that doesn't
work, you'll have to patch the mount command to give it a
`bsize' option which sets the data->bsize field in the
mount structure. For (b), the patch to ld.so/ld-linux.so
is similarly simple and I submitted a patch to the maintainer
a long time ago which does this.

See: http://mailbox.tuniv.szczecin.pl/mama/21-unsorted-9746.html
     (and search document for `rjones').

Rich.

-- 
Richard Jones rjones@orchestream.com Tel: +44 171 598 7557 Fax: 460 4461
Orchestream Ltd.  125 Old Brompton Rd. London SW7 3RP PGP: www.four11.com
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