dump: add dotspacemacs variables to control the dump

* new dotvariable dotspacemacs-emacs-pdumper-executable-file
* new dotvariable dotspacemacs-emacs-dumper-dump-file
* dump emacs if dotspacemacs-emacs-pdumper-executable-file is non nil

core/core-configuration-layer.el

@@ -609,7 +609,9 @@ To prevent package from being installed or uninstalled set the variable
     (configuration-layer//load-layers-files configuration-layer--used-layers
                           '("keybindings.el"))
     (dotspacemacs|call-func dotspacemacs/user-load "Calling dotfile user-load...")
-    (spacemacs|unless-dumping (spacemacs/dump-emacs)))
+    (when (and dotspacemacs-emacs-pdumper-executable-file
+               (file-exists-p dotspacemacs-emacs-pdumper-executable-file))
+      (spacemacs|unless-dumping (spacemacs/dump-emacs))))
   (run-hooks 'configuration-layer-post-load-hook))
 
 (defun configuration-layer/load-auto-layer-file ()

core/core-dotspacemacs.el

@@ -55,6 +55,19 @@ exists. Otherwise, fallback to ~/.spacemacs"))
 `+distributions'. For now available distributions are `spacemacs-base'
 or `spacemacs'.")
 
+(defvar dotspacemacs-emacs-pdumper-executable-file nil
+  "Absolute file path pointing to emacs 27.1 executable compiled with support
+for the portable dumper (this is currently the branch pdumper).
+If nil then automatic dump of emacs is disabled.")
+
+(defvar dotspacemacs-emacs-dumper-dump-file "spacemacs.pdmp"
+  "File path of Spacemacs dump file. This is the file created by the portable
+dumper. To load it when starting Emacs add the parameter `--dump-file'
+when invoking Emacs 27.1 executable on the command line, for instance:
+./emacs --dump-file=spacedump.pdump
+If the file path is relative, it will be relative to the directory pointed
+by `dotspacemacs-emacs-pdumper-executable-file'.")
+
 (defvar dotspacemacs-gc-cons '(100000000 0.1)
   "Set `gc-cons-threshold' and `gc-cons-percentage' when startup finishes.
 This is an advanced option and should not be changed unless you suspect

core/core-dumper.el

@@ -47,11 +47,17 @@ You should not used this function, it is reserved for some specific process."
 
 (defun spacemacs/dump-emacs ()
   "Dump emacs in a subprocess."
-  (let ((default-directory "~/dev/emacs/src"))
+  (let ((default-directory (file-name-directory
+                            dotspacemacs-emacs-pdumper-executable-file)))
     (make-process
-     :name "spacemacs-dump"
+     :name "spacemacs-dumper"
      :buffer "*spacemacs-dumper*"
-     :command (list "~/dev/emacs/src/emacs" "--batch" "-l" "~/.emacs.d/dump-init.el" "-eval" "(dump-emacs-portable \"spacedump.pdmp\")"))))
+     :command (list dotspacemacs-emacs-pdumper-executable-file
+                    "--batch"
+                    "-l" "~/.emacs.d/dump-init.el"
+                    "-eval" (concat "(dump-emacs-portable \""
+                                    dotspacemacs-emacs-dumper-dump-file
+                                    "\")")))))
 
 ;; ;; Brute-force load all .el files in ELPA packages
 ;; (dolist (d (directory-files package-user-dir t nil 'nosort))

core/templates/.spacemacs.template

@@ -441,7 +441,22 @@ If you are unsure, try setting them in `dotspacemacs/user-config' first."
 This function is called while dumping Spacemacs configuration. You can
 `require' or `load' the libraries of your choice that will be included
 in the dump."
-  )
+  (setq-default
+
+   ;; Absolute file path pointing to emacs 27.1 executable compiled with support
+   ;; for the portable dumper (this is currently the branch pdumper)
+   ;; If nil then automatic Emacs dump is disabled.
+   ;; (default nil)
+   dotspacemacs-emacs-pdumper-executable-file nil
+
+   ;; File path of Spacemacs dump file. This is the file created by the portable
+   ;; dumper. To load it when starting Emacs add the parameter `--dump-file'
+   ;; when invoking Emacs 27.1 executable on the command line, for instance:
+   ;;   ./emacs --dump-file=spacedump.pdump
+   ;; If the file path is relative, it will be relative to the directory pointed
+   ;; by `dotspacemacs-emacs-pdumper-executable-file'.
+   ;; (default spacedump.pdmp)
+   dotspacemacs-emacs-dumper-dump-file "spacemacs.pdmp"))
 
 (defun dotspacemacs/user-config ()
   "Configuration for user code: