Function heap_end_vaddr 

pub fn heap_end_vaddr() -> u64

Return the virtual address of the last byte of the HEAP_MEMORY array.

Used by the memory management init code when __kernel_end translation fails. The heap is the largest BSS object; its end address is a tight lower bound on the kernel’s physical extent.

Safety

Accesses the static HEAP_MEMORY address. This is safe because we only compute the pointer value – we do not read from or write to it.