01/03: vm: Transparently compress iso9660 images.

[guix-commits]

nckx pushed a commit to branch master
in repository guix.

commit 26c1bd9dfafb5a954d2174b7a000304cd7ae6345
Author: Tobias Geerinckx-Rice <address@hidden>
AuthorDate: Mon Apr 6 17:48:21 2020 +0200

    vm: Transparently compress iso9660 images.
    
    * gnu/build/vm.scm (make-iso9660-image): Use the ‘--zisofs’ xorriso
    filter at the highest compression settings for supported directories.
---
 gnu/build/vm.scm | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/gnu/build/vm.scm b/gnu/build/vm.scm
index 79eed48..9caa110 100644
--- a/gnu/build/vm.scm
+++ b/gnu/build/vm.scm
@@ -5,6 +5,7 @@
 ;;; Copyright © 2017 Mathieu Othacehe <address@hidden>
 ;;; Copyright © 2017 Marius Bakke <address@hidden>
 ;;; Copyright © 2018 Chris Marusich <address@hidden>
+;;; Copyright © 2020 Tobias Geerinckx-Rice <address@hidden>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -533,6 +534,24 @@ GRUB configuration and OS-DRV as the stuff in it."
                 ;; Set all timestamps to 1.
                 "-volume_date" "all_file_dates" "=1"
 
+                ;; ‘zisofs’ compression reduces the total image size by ~60%.
+                "-zisofs" "level=9:block_size=128k" ; highest compression
+                ;; It's transparent to our Linux-Libre kernel but not to GRUB.
+                ;; Don't compress the kernel, initrd, and other files read by
+                ;; grub.cfg, as well as common already-compressed file names.
+                "-find" "/" "-type" "f"
+                ;; XXX Even after "--" above, and despite documentation 
claiming
+                ;; otherwise, "-or" is stolen by grub-mkrescue which then 
chokes
+                ;; on it (as ‘-o …’) and dies.  Don't use "-or".
+                "-not" "-wholename" "/boot/*"
+                "-not" "-wholename" "/System/*"
+                "-not" "-name" "unicode.pf2"
+                "-not" "-name" "bzImage"
+                "-not" "-name" "*.gz"   ; initrd & all man pages
+                "-not" "-name" "*.png"  ; includes grub-image.png
+                "-exec" "set_filter" "--zisofs"
+                "--"
+
                 "-volid" (string-upcase volume-id)
                 (if volume-uuid
                     `("-volume_date" "uuid"