Subject: Re: bug#34206: Pdumper giving a segfault

From: Eli Zaretskii <[email-masked]>
Date: Sat, 26 Jan 2019 10:06:26 +0200

> From: Compro Prasad <[email-masked]>
> Date: Sat, 26 Jan 2019 12:03:59 +0530
> 
> Emacs source: official master branch (commit: 7960951d5d)
> Emacs config: https://github.com/Compro-Prasad/spacemacs/tree/pdumper-is-in-master
> (commit: f5eef2127ad4d)
> Spacemacs config: https://github.com/Compro-Prasad/.spacemacs.d
> (commit: 8a1eebc65f9a)
> 
> Build command: ./configure --enable-checking='yes,glyphs'
> --enable-check-lisp-object-type CFLAGS='-O0 -g3' --with-xwidgets &&
> make -j2
> 
> GDB log: https://pastebin.com/2uMPHCRV

This seems to indicate your configuration is quite complex, and I
cannot easily understand what are you doing that is different from
the normal build and "emacs -Q" to start Emacs.  In particular, this:

  $ gdb ./src/emacs-27.0.50.11
  Reading symbols from ./src/emacs-27.0.50.11...done.
  (gdb) r --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"
  Starting program: /home/compro/Downloads/git.savannah.gnu.org/git/emacs/src/emacs-27.0.50.11 --dump-file="/home/compro/.emacs.d/.cache/dumps/spacemacs.pdmp"

indicates that your pdump file is spacemacs.pdmp, but I don't know how
that file was produced, and I cannot easily understand what is
different in your build procedure from the normal upstream build of
Emacs.

Maybe you should first take this up with then maintainers of the
Compro-Prasad/spacemacs package.

> OS: Antergos(Arch Linux)
> Compiler: gcc version 8.2.1 20181127 (GCC)
> 
> Can't provide further information because Emacs segfaults before it
> can load any elisp packages while loading the dump file.

The backtrace indicates that it segfaults _after_ loading the dump
file, inside the call to init_buffer.

> I might be doing something wrong here. Can you please guide me how to
> use the pdumper in Emacs or what info topic is it under?

There's no difference in how pdump'ed Emacs should be used, it's the
same as you'd use an unexec'ed Emacs.

I suggest to file an issue with the maintainers of
Compro-Prasad/spacemacs.