Re: `exec shield' test in configure too strict?

[Jan D.]

> Recently Emacs' configure script has been changed to check for the
> presence of linux `exec shield' functionality, by looking for the file
> /proc/sys/kernel/exec-shield, and seeing if it as a non-zero value.  If
> it is present and enabled, and there's no `setarch' program available,
> configure will give an error message and abort.  The reason for this, 
> as
> I understand it, is that emacs cannot dump on such a system unless it
> can use the `setarch' program.
>
> However this test seems too strict:  On fencepost.gnu.org, exec-shield
> is enabled:
>
>    $ cat /proc/sys/kernel/exec-shield
>    1
>
> and there is no setarch program:
>
>    $ type setarch
>    bash: type: setarch: not found
>
> and so emacs refuses to configure -- but if disable this test by doing:
>
>    $ make ac_cv_file__proc_sys_kernel_exec_shield=no
>
> Then Emacs configures and dumps just fine, despite not using `setarch'.

Do that machine have a /proc/sys/kernel/exec-shield-randomize file?

It is the random start address of the heap that makes dumping fail.
A test that explicitly tests for this would be best, but I'm not
sure how portable such a test would be.  Simpler then to test the
contents of /proc/sys/kernel/exec-shield-randomize if this file exists.

        Jan D.