[PATCH] maint: Do not xz-compress ISO images.

[Ludovic Courtès]

The xz-compressed image is 23% smaller than the original ISO image (with
built-in zlib compression), but the extra decompression step is
unconventional and often a hindrance for users.  See discussion at
<https://lists.gnu.org/archive/html/guix-devel/2021-04/msg00497.html>.

* Makefile.am (release): Do not compress ISO images.
* doc/guix.texi (USB Stick and DVD Installation): Remove ".xz" suffix
from URL and file name.
(Copying to a USB Stick, Burning on a DVD): Remove introductory words,
@enumerate, and first item.
---
 Makefile.am   |  6 +++---
 doc/guix.texi | 30 +++---------------------------
 2 files changed, 6 insertions(+), 30 deletions(-)

Hi!

This takes the simple step of providing plain ISOs only (rather than
.iso + .iso.xz as some suggested).

One advantage is that, unless I’m mistaken, this can be done without
breaking string freeze.

We’ll also have to update <https://guix.gnu.org/en/download> on the
release day.

Thoughts?

Ludo’.

diff --git a/Makefile.am b/Makefile.am
index 8d059eb033..623b1c497f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -886,9 +886,9 @@ release: dist-with-updated-version all
            echo "failed to produced Guix installation image for $$system" >&2 
;        \
            exit 1 ;                                                            
        \
          fi ;                                                                  
        \
-         xz < "$$image" > 
"$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso.xz.tmp" ;      \
-         mv "$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso.xz.tmp"      
        \
-            "$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso.xz" ;        
        \
+         cp "$$image" 
"$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso.tmp" ;     \
+         mv "$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso.tmp"         
        \
+            "$(releasedir)/$(GUIX_SYSTEM_IMAGE_BASE).$$system.iso" ;           
        \
        done
 # Generate the VM images.
        for system in $(GUIX_SYSTEM_VM_SYSTEMS) ; do                            
        \
diff --git a/doc/guix.texi b/doc/guix.texi
index 2fe7ad3a2a..3460c58cbc 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -2099,7 +2099,7 @@ about their support in GNU/Linux.
 
 An ISO-9660 installation image that can be written to a USB stick or
 burnt to a DVD can be downloaded from
-@indicateurl{@value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso.xz},
+@indicateurl{@value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso},
 where you can replace @code{x86_64-linux} with one of:
 
 @table @code
@@ -2115,8 +2115,8 @@ Make sure to download the associated @file{.sig} file and 
to verify the
 authenticity of the image against it, along these lines:
 
 @example
-$ wget 
@value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso.xz.sig
-$ gpg --verify guix-system-install-@value{VERSION}.x86_64-linux.iso.xz.sig
+$ wget 
@value{BASE-URL}/guix-system-install-@value{VERSION}.x86_64-linux.iso.sig
+$ gpg --verify guix-system-install-@value{VERSION}.x86_64-linux.iso.sig
 @end example
 
 If that command fails because you do not have the required public key,
@@ -2140,17 +2140,6 @@ It is meant to be copied @emph{as is} to a large-enough 
USB stick or DVD.
 
 @unnumberedsubsec Copying to a USB Stick
 
-To copy the image to a USB stick, follow these steps:
-
-@enumerate
-@item
-Decompress the image using the @command{xz} command:
-
-@example
-xz -d guix-system-install-@value{VERSION}.x86_64-linux.iso.xz
-@end example
-
-@item
 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
 its device name.  Assuming that the USB stick is known as @file{/dev/sdX},
 copy the image with:
@@ -2161,21 +2150,9 @@ sync
 @end example
 
 Access to @file{/dev/sdX} usually requires root privileges.
-@end enumerate
 
 @unnumberedsubsec Burning on a DVD
 
-To copy the image to a DVD, follow these steps:
-
-@enumerate
-@item
-Decompress the image using the @command{xz} command:
-
-@example
-xz -d guix-system-install-@value{VERSION}.x86_64-linux.iso.xz
-@end example
-
-@item
 Insert a blank DVD into your machine, and determine
 its device name.  Assuming that the DVD drive is known as @file{/dev/srX},
 copy the image with:
@@ -2185,7 +2162,6 @@ growisofs -dvd-compat -Z 
/dev/srX=guix-system-install-@value{VERSION}.x86_64-lin
 @end example
 
 Access to @file{/dev/srX} usually requires root privileges.
-@end enumerate
 
 @unnumberedsubsec Booting
 
-- 
2.31.1