initramfs-tools: use upstream's xz handling to support multithreading

initramfs-tools versions >=0.136 support multithreading in
xz compression usage (see upstream commit 41d9ceb3).

While at it fix header comment, to refer to the actual
script (which was renamed in commit 6e778099).

FTR: we're still using xz (and not using e.g. zstd) because
it still seems to be the combination of small file size
*and* decompression speed now that we have multithreading
support (though zstd might be an interesting option in the future),
also see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=976054

diff --git a/etc/grml/fai/config/files/etc/initramfs-tools/conf.d/xz-compress/GRMLBASE b/etc/grml/fai/config/files/etc/initramfs-tools/conf.d/xz-compress/GRMLBASE
index 3631ac8..613eb4b 100644 (file)
--- a/etc/grml/fai/config/files/etc/initramfs-tools/conf.d/xz-compress/GRMLBASE
+++ b/etc/grml/fai/config/files/etc/initramfs-tools/conf.d/xz-compress/GRMLBASE
@@ -1,10 +1,5 @@
-# This file is installed by grml-live in 10-build-initramfs.
+# This file is installed by grml-live in 80-initramfs.
 # Its purpose is to use XZ compression when building initramfs.
 
-# this is a workaround to pass custom options to the xz compression
-xz() {
-    command xz --check=crc32
-}
-
-# enable XZ compression, reducing initramfs size from ~17MB to ~12MB
-compress=xz
+# enable XZ compression, reducing initramfs size from ~50MB to ~33M
+COMPRESS=xz