ci: compress squashfs with zstd

Compress squashfs with zstd since that now we have
CONFIG_SQUASHFS_ZSTD=y in all our guest kernels.

In my tests it is 78MB vs 85MB (an 8.2% reduction)

Signed-off-by: Pablo Barbáchano <[email protected]>

Author: pb8o

resources/guest_configs/ci.config

@@ -1,6 +1,7 @@
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
 CONFIG_MSDOS_PARTITION=y
+CONFIG_SQUASHFS_ZSTD=y
 # aarch64 only TBD split into a separate file
 CONFIG_DEVMEM=y
 # CONFIG_ARM64_ERRATUM_3194386 is not set

resources/rebuild.sh

@@ -79,10 +79,9 @@ EOF
     id_rsa=$OUTPUT_DIR/$ROOTFS_NAME.id_rsa
     cp id_rsa $id_rsa
 
-    # -comp zstd but guest kernel does not support
     rootfs_img="$OUTPUT_DIR/$ROOTFS_NAME.squashfs"
     mv $rootfs/root/manifest $OUTPUT_DIR/$ROOTFS_NAME.manifest
-    mksquashfs $rootfs $rootfs_img -all-root -noappend
+    mksquashfs $rootfs $rootfs_img -all-root -noappend -comp zstd
     rm -rf $rootfs
     for bin in fast_page_fault_helper fillmem init readmem; do
         rm $PWD/overlay/usr/local/bin/$bin