rv64im_min_nndev.nx

rv64im_min_nndev.nx -- the NISHI-NATIVE DEVICE PROTOCOL (NNDP) device model. The genuine "exceed virtio" target (nishi-ecosystem-only law: virtio is the last-mile/benchmark transport, NOT the substrate -- the NATIVE protocol that EXCEEDS it is the real goal, the census `sovereign-device-protocol` ABSENT exceed-row). NNDP is a SOVEREIGN, deliberately LEAN block device protocol designed to complete one I/O in FAR fewer MMIO accesses + memory ops than legacy virtio-MMIO -- measured head-to-head on the SAME sovereign rv64 emu (apples-to-apples). Why it is leaner than virtio-MMIO (the measurable exceed): - SELF-DESCRIBING IDENTITY: MAGIC + DEVCLASS (2 reads), no Version/VendorID/HostFeatures/ GuestFeatures negotiation. - SINGLE-STEP BRING-UP: one ENABLE write, NOT the 4-stage ACK->DRIVER->FEATURES_OK->DRIVER_OK Status handshake (+ the FEATURES_OK re-read). - NO SPLIT VIRTQUEUE: one INLINE command descriptor at CMD_ADDR (data_addr/len/op), NOT a descriptor table + avail ring + used ring with index bookkeeping and TWO notify kicks. - SINGLE DOORBELL, DIRECT COMPLETION: one DOORBELL write -> the device DMA-processes the command and latches STATUS + RESULT inline; the driver reads them back directly (no used-ring walk, no used.idx/avail.idx, no separate status descriptor). Register window @ NX_NNDEV_BASE (256 bytes), an INDEPENDENT instance (virtio/nvme untouched): 0x00 MAGIC (RO) 0x4E4E4431 ("NND1", little-endian) -- identity, self-describing 0x04 DEVCLASS (RO) 1 = block 0x08 ENABLE (RW) driver writes 1 to bring the device up (single-step); read-back = latched 0x0C CMD_ADDR (RW) guest-physical address of the inline command descriptor; read-back = latched 0x10 DOORBELL (WO) write 1 -> device runs the command at CMD_ADDR (DMA) and completes inline 0x14 STATUS (RO) completion status latched on the last doorbell (0 = OK) 0x18 RESULT (RO) first 32-bit word the device DMA-read from the command's data buffer (the data round-trip binding proof; the driver reads it back == its written word) Inline command descriptor (at CMD_ADDR in guest RAM): +0 data_addr (4, low 32 of the data-buffer guest-physical address) +4 data_len (4) +8 op (4; 0 = read/round-trip) Status: SEED 2026-06-13 (X-DRV sovereign-device-protocol). Block read round-trip + identity + single-step enable + single-doorbell completion. license_tier: ORIGINAL