Re: New dumping problem...

[Jan D.]

David Kastrup wrote:

> On the newest Fedora Core tests, the setarch i386 workaround is no
> longer sufficient for dumping.
>
> It turns out that one way to fix this is to use
>
>  echo 0 >/proc/sys/kernel/randomize_va_space
>
> (which only root can do).
>
> Uh oh.
>  

Hmm, there is not much documentation of this, but what I can find is 
that this is a general feature in the Linux kernel from 2.6.11 or 
2.6.12-rc1, so other GNU/Linux distributions may also have it.  
Apparently it also breaks dosemu.

> The error message is
>
> Dumping under names emacs and emacs-22.0.50
> **************************************************
> Warning: Your system has a gap between BSS and the
> heap (6716260 byte).  This usually means that exec-shield
> or something similar is in effect.  The dump may
> fail because of this.  See the section about 
> exec-shield in etc/PROBLEMS for more information.
> **************************************************
> make[1]: *** [bootstrap-emacs] Segmentation fault
> make[1]: Leaving directory `/usr/local/tmp/emacs-build/src'
> make: *** [bootstrap-build] Error 2
>
> It seems like we are playing catchup with the operating system's
> security games.
>  

Indeed.  The final solution must be to either fix unexec (ELF I presume) 
or move away from unexec to something else.  I think the only thing we 
can do for now is to note this in etc/PROBLEMS.  It is too bad that root 
access is required on those systems to build Emacs.

   Jan D.