Re: can't dump emacs-21.1 on redhat 7.1 nfs-mounted file system

[Eli Zaretskii]

On 28 Oct 2001, Dale Hagglund wrote:

>         (a) nfs build directory, no configure options; 
> 
>         (b) nfs build directory, --disable-largefile; and
> 
>         (c) local build directory, no configure options.
> 
> Both (a) and (b) exhibit the same problem.  (c) creates a proper
> dumped emacs.
> 
> I've investigated somewhat, and it appears that the undump process
> uses the mmap system call on linux.  So, it appears there's either a
> generic linux problem with mmap on nfs-mounted file systems, or some
> sort of incompatibility between the linux nfs client and the freebsd
> nfs server.

Thank you for a detailed report and the investigations that followed.

What we know from the pretest is consistent with your results: local
builds work, while NFS-mounted filesystems sometimes don't, and when
that happens, users get a file full of binary zeroes.

> I did a bit of web searching, and in at least some corners of the
> world, mixing mmap and nfs is not considered highly likely to work in
> general.

Is it possible to come up with a change for unexelf.c to not use mmap,
either always or on NFS-mounted volumes?