64 bit emacs on AIX

64 bit emacs on AIX

[Perry Smith]

I'd like to get emacs compiled in 64 bit mode working on AIX.  It got it to
compile.  It does not dump but I am hoping I can work on that so right now,
I just start start temacs and let it load the init files.

I discovered that I can not execute other programs from inside emacs.  For
example, dired dies with

dired-insert-directory: Searching for program: No such file or directory, ls

and the last entry on the stack is call-process.  It looks like
call-process calls openp which must return the error.  openp I assume calls
faccessat because X_OK is passed in as the predicate to openp.

"ls" is going to be a 32 bit executable but there should not be any reason
I can't fork / exec to a 32 bit executable from a 64 bit executable.  I'm
guessing that openp / faccessat is not happy.

Short of adding printf's, any suggestions on how to debug this?  I doubt if
gdb / dbx will work but I guess it might.

Anyone have an educated guess (based upon past battle scars) as to what
might be going on?

Thank you for your help,
Perry

Re: 64 bit emacs on AIX

[Christopher Wellons]

I ran into this problem using a non-dumped Emacs (CANNOT_DUMP=yes) on 
x86-64. The problem is temacs either doesn't set exec-path or it sets it 
to nil — I'm not sure which. There's a bug in call-process that prevents 
it from working correctly even for absolute paths when exec-path is nil. 
The bug comes from the for loop in openp(), which requires at least one 
iteration to successfully resolve an absolute path (so *any* non-empty 
exec-path list will do).

This combination of issues makes it appear that temacs can't run 
subprocesses, but it really just needs some help.

Re: 64 bit emacs on AIX

[Eli Zaretskii]

> Date: Tue, 20 Feb 2018 20:28:11 -0500
> From: Christopher Wellons <wellons@nullprogram.com>
> 
> I ran into this problem using a non-dumped Emacs (CANNOT_DUMP=yes) on 
> x86-64. The problem is temacs either doesn't set exec-path or it sets it 
> to nil — I'm not sure which.

I don't understand how this happens in your case, exec-path is set in
init_callproc and init_clallproc_1, both called by temacs during
startup.  Can you try figuring out why this doesn't happen for you?

Re: 64 bit emacs on AIX

[Glenn Morris]

Eli Zaretskii wrote:

>> I ran into this problem using a non-dumped Emacs (CANNOT_DUMP=yes) on 
>> x86-64. The problem is temacs either doesn't set exec-path or it sets it 
>> to nil — I'm not sure which.
>
> I don't understand how this happens in your case, exec-path is set in
> init_callproc and init_clallproc_1, both called by temacs during
> startup.

loadup.el sets it.

In any case, I suspect this was fixed last year by

http://lists.gnu.org/archive/html/emacs-diffs/2017-04/msg00058.html

Re: 64 bit emacs on AIX

[Glenn Morris]

PS apparent context for this thread:

http://lists.gnu.org/r/help-gnu-emacs/2017-01/msg00130.html


(Replying to a year old message without citing it at all is a little odd...)