nx_gpu_mem_gate.nx

nx_gpu_mem_gate.nx -- gpu GP6 heaps and residency on the real device, driven directly through nx_gpu_mem. Teeth: the budget is READ from the device for both segment groups; a bounded window of heaps (well under the budget) is allocated, placed and made resident; every heap is then EVICTED through the device's own EVICT and the proof of eviction is the device's own paging answer -- a make-resident after the evict returns DXG_MKRES_PENDING, where a heap that was never evicted answers 0. Tampers: an evict of a bogus handle is refused; a budget query for an invalid segment group is refused; and a positive control after the tampers reads the same local budget back. THE THIRD STATE: absent /dev/dxg (every host but the GPU laptop) is a gv_need precondition -> SKIP, never RED. SCOPE the board carries: the heaps are non-local (sysmem-backed, UMD-less); exhausting the LOCAL segment to force driver-initiated eviction needs VRAM allocations the vendor UMD owns, and exhausting the non-local segment would exhaust the host's RAM -- so this gate proves the EVICT MECHANISM and the budget accounting, not budget exhaustion. license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0 (or 3 = SKIP where there is no /dev/dxg)