download the toolchain 

https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.8/+/android-5.1.1_r13

place on

prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.8

## 	TARGET_DEVICE=hd  (A500CG/A501CG/A600CG - default)

For building kerne from source

1 make -f KernelMakefile TARGET_DEVICE=hd build_kernel
 or
1 make -f KernelMakefile TARGET_DEVICE=hd modules_install

after building the kernel from source this is how to generate the .dep files needed
modules.alias
modules.alias.bin
modules.builtin.bin
modules.dep
modules.dep.bin
modules.devname
modules.softdep
modules.symbols
modules.symbols.bin

that file is generated and need if zenfone 5 kernel run with modules i suggest to fix the kernel to be run
all modules to be built in

the command need to generate this file is beloc in you terminal

make -f KernelMakefile TARGET_DEVICE=hd copy_modules_to_root

after success you will find all module on out/target/product/asusctp_hd/root

copy ramdisk and start to pack the kernel

pack ramdisk.cio.gz

find . | cpio -o -H newc | gzip > ../ramdisk.cpio.gz

pach the boot image 

Teminal command for pack

pack_intel boot.img bzImage ramdisk.cpio.gz new_boot.img

Teminal command for unpack

unpack_intel boot.img bzImage ramdisk.cpio.gz