experiments with alternate root fs

btrfs.sh

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+#!/bin/bash
+set -e
+
+# Variables
+ROOTFS_DIR="build/agnos-rootfs"
+IMAGE_NAME="agnos-btrfs-test.img"
+IMAGE_SIZE="4G"  # Adjust this according to your needs
+
+# Check if the rootfs directory exists
+if [ ! -d "$ROOTFS_DIR" ]; then
+  echo "Error: $ROOTFS_DIR does not exist."
+  exit 1
+fi
+
+# Create an empty image file
+dd if=/dev/zero of=$IMAGE_NAME bs=1 count=0 seek=$IMAGE_SIZE
+
+# Format the image with BTRFS
+mkfs.btrfs -f -d compress -m compress $IMAGE_NAME
+
+# Mount the image to a temporary directory
+MOUNT_POINT=$(mktemp -d)
+sudo mount -o loop $IMAGE_NAME $MOUNT_POINT
+
+# Copy the rootfs to the mounted image
+sudo cp -a $ROOTFS_DIR/* $MOUNT_POINT/
+
+# Unmount the image
+sudo umount $MOUNT_POINT
+
+# Clean up the temporary mount point
+rmdir $MOUNT_POINT
+
+echo "BTRFS image $IMAGE_NAME created successfully."

btrfs2.sh

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+#!/bin/bash
+
+# Variables
+ROOTFS_DIR="build/agnos-rootfs"
+IMAGE_NAME="agnos-btrfs-test.img"
+IMAGE_SIZE="4G"  # Adjust this according to your needs
+
+# Create an empty image file
+dd if=/dev/zero of=$IMAGE_NAME bs=1 count=0 seek=$IMAGE_SIZE
+
+# Format the image with BTRFS, enabling compression for both data and metadata
+mkfs.btrfs -f $IMAGE_NAME
+
+# Create a loop device and mount it
+LOOP_DEVICE=$(sudo losetup -f --show $IMAGE_NAME)
+MOUNT_POINT=$(mktemp -d)
+
+# Enable compression for the filesystem
+sudo mount -o loop,compress-force=zlib:15 $LOOP_DEVICE $MOUNT_POINT
+#sudo mount -o loop,compress=zlib:15,compress-force=zlib:15 $LOOP_DEVICE $MOUNT_POINT
+#sudo mount -o loop $LOOP_DEVICE $MOUNT_POINT
+
+# Copy the rootfs to the mounted image
+sudo cp -a $ROOTFS_DIR/* $MOUNT_POINT/
+
+#sudo btrfs filesystem defragment -r -v -clzo $MOUNT_POINT
+
+# Unmount the image
+sudo umount $MOUNT_POINT
+
+# Detach the loop device
+sudo losetup -d $LOOP_DEVICE
+
+# Clean up the temporary mount point
+rmdir $MOUNT_POINT
+
+echo "BTRFS image $IMAGE_NAME with compression created successfully."
+du -hs $IMAGE_NAME

btrfs3.sh

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+#!/bin/bash
+
+# Directory containing the root filesystem
+ROOTFS_DIR="build/agnos-rootfs"
+
+# Output file name for the BTRFS image
+IMAGE_FILE="agnos-rootfs.img"
+
+# Temporary directory for the BTRFS filesystem
+TEMP_DIR=$(mktemp -d)
+
+# Size for the initial BTRFS image (adjust as necessary)
+INITIAL_SIZE="10G"
+
+# Compression to use for BTRFS (LZO is commonly supported, but ZSTD might be better if available)
+COMPRESSION="lzo"  # or "zstd" if your kernel supports it
+
+# Create a BTRFS filesystem in a loopback file
+truncate -s "$INITIAL_SIZE" "$IMAGE_FILE"
+mkfs.btrfs --compress=$COMPRESSION "$IMAGE_FILE"
+
+# Mount the BTRFS filesystem
+sudo mount -o compress=$COMPRESSION "$IMAGE_FILE" "$TEMP_DIR"
+
+# Copy the rootfs into the mounted BTRFS filesystem
+sudo rsync -aHAXx --info=progress2 "$ROOTFS_DIR"/ "$TEMP_DIR"/
+
+# Unmount the filesystem
+sudo umount "$TEMP_DIR"
+
+# Attempt to shrink the filesystem
+sudo losetup -fP "$IMAGE_FILE"
+LOOPDEV=$(losetup -j "$IMAGE_FILE" | awk '{print $1}' | sed 's/://')
+sudo btrfs filesystem resize min /dev/$LOOPDEV
+sudo btrfs check --repair /dev/$LOOPDEV
+sudo losetup -d /dev/$LOOPDEV
+
+# Resize the image file to the actual size of the filesystem
+# Note: This step requires knowing or estimating the exact size needed
+# Here, we'll use the size of the last block used by BTRFS
+SIZE=$(sudo btrfs inspect-internal dump-super "$IMAGE_FILE" | grep "total bytes" | awk '{print $3}')
+truncate -s "$SIZE" "$IMAGE_FILE"
+
+# Clean up
+rmdir "$TEMP_DIR"
+
+echo "BTRFS image created and shrunk: $IMAGE_FILE"

squashfs.sh

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+#!/bin/bash
+
+rm -rf output/system.squash*
+
+#mksquashfs build/agnos-rootfs output/system.squashfs.lzo -comp lzo -b 1M -no-xattrs
+#sudo mksquashfs build/agnos-rootfs output/system.squashfs.gzip -comp gzip -Xcompression-level 1 -b 1M -no-xattrs
+sudo mksquashfs build/agnos-rootfs output/system.squashfs.lz4 -comp lz4 -b 4k -no-fragments -no-xattrs # -no-acls
+
+du -hs output/sys*