can you explain how you generated your initramfs.cpio.gz ? I am not really familiar with building an initramfs directly, I have some experience with building the kernel using make menuconfig to build a kernel for Xen or KVM with different options like to change the VPCI to frontend or backend for Xen, but I have never really had to customize or build initramfs directly
most of the time when you build a kernel with make -j8 rpm or make -j8 deb-pkg, the resulting package files will automatically generate an initramfs.img for the kernel
can you also post your .config file for this bzImage you posted? from the top level directory of where ps4-linux was that matches this bzImage?