#Rocketfan's notes on creating the overclock update.
#Most of this I do with linux commands (except the restool stuff - could only find it for Windows).

#This unpacks the outer image container.
mkdir here
img_unpack atari_update.img here
cd here

#This unpacks the "inner" update.image file (and creates the update folder).
afptool -unpack update.img update

#Now with the resource.img you need the windows command restool.exe to unpack it and later (after updating the device tree) repack it.  
Usage:
ResTool.exe [-unpack resource.img] [-pack <file1 file2 fileN>]
In my case restool.exe is sitting one folder above.
Example unpack: ..\ResTool.exe -unpack resource.img


#After restool -unpack you have a .dtb you need to "uncompile it" into a .dts (text format) to edit it.
dtc -I dtb -O dts rk-kernel.dtb -o rk-kernel.dts

#Now you finally have a file you can mod with the overclock.  (rk-kernel.dts).
#I was luck to have the old (LFB) file I could just steal the oveclock values for the OPP.  When I tried to go higher it only froze the system.
#PS - those clock values are not random numbers.  The CPU only supports a limited number of specific set points, and they can be found on the Internet if you search hard enough.

#Re-creating the new .dtb from the modified .dts
dtc -I dts -O dtb rk-kernel.dts -o rk-kernel_new.dtb

#Now go back to windows and repack the new .dtb (renamed to just rk-kernel.dtb) into the resourc.img using restool.exe 
Example pack (create the new resource.img): ..\ResTool.exe -pack rk-kernel.dtb logo.bmp logo_kernel.bmp 

#Now the actual update .img file needs to be made.

#rebuilding the inner update with the afptool - in my case, I had only these files for the inner part of the overclock update:
package-file
parameter
RESERVED
resource.img

#The goal being only to modify the resource partition with the overclock.

#afptool makes the "inner" file
afptool -pack . ../update_new.img  

#Next use "img_maker" to build the "outer" update package.
img_maker -rk30 loader.img update.img release_update_new.img