[gnome-build-meta/abderrahim/xz-image] vm/image.bst: generate xz compressed raw image instead of qcow2

[Abderrahim Kitouni <akitouni src gnome org>]

commit 86f5403949a250595550d59e4fea468130a58d0a
Author: Abderrahim Kitouni <akitouni gnome org>
Date:   Wed Jul 1 12:24:05 2020 +0100

    vm/image.bst: generate xz compressed raw image instead of qcow2
    
    The resulting image is smaller to download, can be reused for the iso images,
    and xz can recreate sparse files when unpacking.

 elements/vm/image.bst | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)
---
diff --git a/elements/vm/image.bst b/elements/vm/image.bst
index 6d8d7900..2922ec25 100644
--- a/elements/vm/image.bst
+++ b/elements/vm/image.bst
@@ -22,13 +22,15 @@ variables:
 
 environment:
   OSTREE_REPO: "%{sysroot}/ostree/repo"
+  XZFLAGS: -T%{max-jobs}
+
+environment-nocache:
+- XZFLAGS
 
 config:
   layout:
   - element: ''
     destination: '/sysroot'
-  - element: ''
-    destination: '/genimage'
   - element: vm/repo.bst
     destination: '/source-repo'
   - element: core-deps/libostree.bst
@@ -70,7 +72,7 @@ config:
     cp -r "%{sysroot}"/ostree/boot.1/gnome-os/*/*/boot/EFI/ "%{sysroot}/boot/"
 
   - |
-    cat >/genimage/genimage.cfg <<EOF
+    cat > %{install-root}/genimage.cfg <<EOF
     image efi.img {
         vfat {
             extraargs = "-F32 -n EFI"
@@ -102,13 +104,12 @@ config:
     EOF
 
   - |
-    cd /genimage
+    cd %{install-root}
     genimage --rootpath "%{sysroot}"
+    mv images/disk.img .
+    rm -rf genimage.cfg images/ tmp/
 
   # FIXME: Propose support for part attrs in genimage project
-  - sfdisk --part-attrs /genimage/images/disk.img 2 55
+  - sfdisk --part-attrs %{install-root}/disk.img 2 55
 
-  - |
-    qemu-img convert -f raw -O qcow2 \
-        /genimage/images/disk.img \
-        "%{install-root}/disk.qcow2"
+  - xz ${XZFLAGS} %{install-root}/disk.img