I pushed latest my rkutils to https://github.com/naobsd/rkutils
rkunpack can unpack RKFW image used in RK2918 ROM, RKAF image (update.img), KRNL/PARM image used in some single partition image. unpack will be done recursively.
rkcrc can make KRNL/PARM images with -k/-p.
rkafpack can make RKAF image. (I need to write docs/howtos...)
latest RK2918 ROMs which is based on "SDK2.0", new format for boot.img/recovery.img is introduced. it's almost same as common boot.img format for android. unpackbootimg/mkbootimg can be used to unpack/repack it with one exception...
there is SHA1 hash value in header of boot.img (offset 0x240 bytes). Rockchip changes it by some unknown way. normal mkbootimg can't generate same hash value as Rockchip, so we can't make custom boot.img with new format
fortunately, we can split new boot.img, and we can make separate kernel.img and boot.img(ramdisk) like as pre-SDK2.0 RK2918 ROMs, which is loadable with new bootloader in SDK2.0 ROMs.
btw I just found interesting one: https://github.com/jhonxie/rk2918_tools