[PATCH] releases: use newer compression methods for tarballs

[Jan Beulich <jbeulich@xxxxxxxx>]

Other projects have long switched to xz and/or lzip.

In the mktarball script, don't rely on the tar used supporting the -J
(xz) or --lzip (lzip) options.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Question (to the release technicians) is whether this would be adding
undue overhead, primarily as a result of anything done outside of the
build system.

It's unclear to me why we have git create a tarball, extract that, just
to then make a tarball again (without any special options, like to
override owner or timestamps; in this context I notice that tarballs
created by Andrew have file ownership of andrew/andrew, while ones made
by Julien use root/root).

Without passing -9, I observe lzip to compress worse than xz; the win
of passing -9 to xz isn't overly big anyway (about 100k, compared to
about 250k with lzip).

lzip, unlike the other two tools, doesn't really show a progress
indicator with -v. Merely having final statistics may make the use of
the option here questionable.

--- a/docs/process/release-technician-checklist.txt
+++ b/docs/process/release-technician-checklist.txt
@@ -119,7 +119,7 @@ RELEASE TARBALL
        make src-tarball           # uses git-describe (best for RCs)
         # ^find some way to add git-cache-proxy to this (done in 
~iwj/.gitconfig)
        mkdir /volatile/iwj/website-thing/xen.org/oss-xen/release/$v
-       mv dist/xen-$v.tar.gz 
/volatile/iwj/website-thing/xen.org/oss-xen/release/$v/.
+       mv dist/xen-$v.tar.[glx]z 
/volatile/iwj/website-thing/xen.org/oss-xen/release/$v/.
 
        # website-thing/xen.org is cvs -d 
mail.xenproject.org:/home/downloads-cvs/cvs-repos co xen.org
        cd /volatile/iwj/website-thing/xen.org
@@ -139,9 +139,12 @@ RELEASE TARBALL
        cvs add -kb oss-xen/release/$v/
 
         cd oss-xen/release/$v
-        gpg --digest-algo=SHA256 --detach-sign -u 'xen tree' xen-$v.tar.gz
-       cvs add -kb xen-$v.tar.gz
-        cvs add -kb xen-$v.tar.gz.sig
+        for t in xen-$v.tar.[glx]z
+        do
+            gpg --digest-algo=SHA256 --detach-sign -u 'xen tree' $t
+            cvs add -kb $t
+            cvs add -kb $t.sig
+        done
         cd ../../..
 
        cvs ci -m $v
@@ -152,6 +155,10 @@ RELEASE TARBALL
        # should show something like
        #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.gz
        #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.gz.sig
+       #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.lz
+       #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.lz.sig
+       #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.xz
+       #   U oss-xen/release/4.8.0-rc2/xen-4.8.0-rc2.tar.xz.sig
 
 After a .0 release, update XEN_EXTRAVERSION again (to .1-pre, see above).
 
--- a/docs/process/xen-release-management.pandoc
+++ b/docs/process/xen-release-management.pandoc
@@ -274,10 +274,10 @@ Xen X.Y rcZ is tagged. You can check tha
 https://xenbits.xen.org/git-http/xen.git X.Y.0-rcZ
 
 For your convenience there is also a tarball at:
-https://downloads.xenproject.org/release/xen/X.Y.0-rcZ/xen-X.Y.0-rcZ.tar.gz
+https://downloads.xenproject.org/release/xen/X.Y.0-rcZ/xen-X.Y.0-rcZ.tar.[glx]z
 
 And the signature is at:
-https://downloads.xenproject.org/release/xen/X.Y.0-rcZ/xen-X.Y.0-rcZ.tar.gz.sig
+https://downloads.xenproject.org/release/xen/X.Y.0-rcZ/xen-X.Y.0-rcZ.tar.[glx]z.sig
 
 Please send bug reports and test reports to xen-devel@xxxxxxxxxxxxxxxxxxxx.
 When sending bug reports, please CC relevant maintainers and me
--- a/tools/misc/mktarball
+++ b/tools/misc/mktarball
@@ -31,4 +31,14 @@ git_archive_into $xen_root $tdir/xen-$de
 
 GZIP=-9v tar cz -f $xen_root/dist/xen-$desc.tar.gz -C $tdir xen-$desc
 
-echo "Source tarball in $xen_root/dist/xen-$desc.tar.gz"
+if [ -n "$(command -v xz)" ]
+then
+  tar c -C $tdir xen-$desc | $(command -v xz) -v -9 
>$xen_root/dist/xen-$desc.tar.xz
+fi
+
+if [ -n "$(command -v lzip)" ]
+then
+  tar c -C $tdir xen-$desc | $(command -v lzip) -v -9 
>$xen_root/dist/xen-$desc.tar.lz
+fi
+
+echo "Source tarball in $xen_root/dist/xen-$desc".tar.[glx]z