[PPC] t1024rdb: CONFIG_KERNEL_START=0x0 equivalent for ppc64 (Kernel 3.16.85)

[Alex Fetzner]

Hello all,

I have a legacy product using linux 3.12.19 that I am updating to use linux 4 and eventually 5. 
The product use an NXT (Freescale) t1024rdb (e5500 processor).
I am right now trying to compile a 3.16.85 kernel that works as a stand-in replacement for the existing kernel. The product uses a u-boot load address 0x1000000 (1MB) and flattened device tree address 0x2000000 (2MB). The deployment of this kernel is such that I cannot alter these address.
The original uImage header has load address and entry point 0x0.
The original vmlinux ELF from the uImage has entry point address 0x0.

How do I appropriately alter a ppc64 kernel to have entry point 0x0?
I can create a uImage header with load and entry point 0x0, but the kernel uses a virtual address 0xc000000000000000 as entry point. 
I see that 32 bit kernels have the configurable option CONFIG_KERNEL_START, but this is not available for 64 bit. 

Kind regards,
AF