buildroot/fs/cpio/Config.in

config BR2_TARGET_ROOTFS_CPIO
	bool "cpio the root filesystem"
	help
	  Build a cpio archive of the root filesystem

choice
        prompt "Compression method"
        default BR2_TARGET_ROOTFS_CPIO_NONE
        depends on BR2_TARGET_ROOTFS_CPIO
        help
          Select compressor for cpio filesystem of the root filesystem

config BR2_TARGET_ROOTFS_CPIO_NONE
        bool "no compression"
        help
         Do not compress the cpio filesystem.

config BR2_TARGET_ROOTFS_CPIO_GZIP
        bool "gzip"
        help
         Do compress the cpio filesystem with gzip.

config BR2_TARGET_ROOTFS_CPIO_BZIP2
        bool "bzip2"
        help
         Do compress the cpio filesystem with bzip2.

config BR2_TARGET_ROOTFS_CPIO_LZMA
        bool "lzma"
        help
         Do compress the cpio filesystem with lzma.

endchoice