Constant CODE_BASE 

pub const CODE_BASE: u32 = 0x0040_0000; // 4_194_304u32

Re-exported PVM2 ABI layout constants (see [nub_program::abi]). Guest virtual address where the (single) code region maps read-only. A PVM PC is CODE_BASE + byte_offset. Sits at 4 MiB so [0, 4 MiB) is an unmapped null guard.