apm821xx: build squashfs-rootfs images for the MBL

This patch adds support for squashfs as the root filesystem.

advantages:
 - migrate from a existing -ext4 installation and back
   with the sysupgrade utility
 - existing partition layout will not be lost during switch
 - slightly smaller image size as compared to the -ext4 image.

disadvantages:
 - needs f2fs + tools. This is because fstools rootdisk.c decides based
   on the partition size (currently root partitions > 100 MiB) f2fs is
   used as the rootfs_data filesystem.
 - rootfs_data is placed into the rootfs partition after the squashfs.
   This makes it difficult for tools that expect a /dev/sda${X} device.
   It also makes it difficult for data recovery tools as they might not
   expect to find a embedded partition or will be slightly confused.
   ... or will not support f2fs.

For people with existing build configurations: make sure to include mkf2fs
and f2fsck packages into the image. Otherwise the new -squashfs image will
only boot from the ram-overlay.

Note:
All overlay data (configurations/all installed packages/...) will be
placed in inside the rootfs partition (i.e. /dev/sda2) just after the
squashfs image.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/target/linux/apm821xx/image/mbl_gen_hdd_img.sh b/target/linux/apm821xx/image/mbl_gen_hdd_img.sh
index 589dcf9150..6536ce9872 100755
--- a/target/linux/apm821xx/image/mbl_gen_hdd_img.sh
+++ b/target/linux/apm821xx/image/mbl_gen_hdd_img.sh
@@ -1,16 +1,16 @@
 #!/usr/bin/env bash
 
 set -x
-[ $# -eq 3 ] || {
-    echo "SYNTAX: $0 <file> <bootfs image> <rootfs image>"
+[ $# -eq 5 ] || {
+    echo "SYNTAX: $0 <file> <bootfs image> <rootfs image> <bootfs size> <rootfs size>"
     exit 1
 }
 
 OUTPUT="$1"
 BOOTFS="$2"
 ROOTFS="$3"
-let "BOOTFSSIZE=(`stat -c%s "$2"` + 1048575) / 1048576"
-let "ROOTFSSIZE=(`stat -c%s "$3"` + 1048575) / 1048576"
+BOOTFSSIZE="$4"
+ROOTFSSIZE="$5"
 
 head=4
 sect=63