ogra@localhost:~$ grep SQUASHFS /snap/pi2-kernel/current/config-4.4.0-1040-raspi2 
CONFIG_SQUASHFS=y
# CONFIG_SQUASHFS_4K_DEVBLK_SIZE is not set
# CONFIG_SQUASHFS_DECOMP_MULTI is not set
# CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU is not set
CONFIG_SQUASHFS_DECOMP_SINGLE=y
# CONFIG_SQUASHFS_EMBEDDED is not set
# CONFIG_SQUASHFS_FILE_CACHE is not set
CONFIG_SQUASHFS_FILE_DIRECT=y
CONFIG_SQUASHFS_FRAGMENT_CACHE_SIZE=3
# CONFIG_SQUASHFS_LZ4 is not set
CONFIG_SQUASHFS_LZO=y
CONFIG_SQUASHFS_XATTR=y
CONFIG_SQUASHFS_XZ=y
CONFIG_SQUASHFS_ZLIB=y