I recently built emacs from the source code and I have some questions about portable dump.

Building process generates bootstrap-emacs.pdmp and emacs.pdmp successively in the last part of building. After that, it executes cp -f emacs.pdmp bootstrap-emacs.pdmp to overwrite it.

My questions are

  1. What is the difference between pdump and pbootstrap method?

  2. Why does building process generates two different dump files, although it will be overwritten soon after that.

1 Answer 1


Have a look at the Elisp Reference Manual which has a helpful section on "Building Emacs" in appendix E1: https://www.gnu.org/software/emacs/manual/html_node/elisp/Building-Emacs.html.

There you learn that bootstrap-emacs.pdmp is an intermediate step:

used while bootstrapping Emacs, when no previous Emacs binary and no *.elc byte-compiled Lisp files are available.

Of course, you can read this from the comfort of yr own emacs: C-h R elisp.

As @Drew said earlier today: Ask Emacs!

  • Thank you very much. I'm going to check the manual.
    – user38323
    Jun 25, 2022 at 5:06

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