DEPRECATED.md

Deprecated: C kernel module

The files at the root of this repository (akida-pcie-core.c, Makefile, install.sh, build_kernel_w_cma.sh) are the original BrainChip C PCIe driver.

They are kept for reference only. All active development is in rust/.

---

Why deprecated

Problem	C module	Rust replacement
Kernel version ceiling	Requires rebuilding per kernel; datasheet states "no plans for updates past 6.8"	VFIO-based Rust driver works without a kernel module
Python SDK dependency	C module required by Python SDK (MetaTF)	Pure Rust — no Python, no C++ SDK, no MetaTF
Permissions	Requires chmod 666 /dev/akida* after every boot	VFIO uses IOMMU for secure isolation per-process
Build toolchain	Needs kernel headers, gcc, make	cargo build --release
Hardware discovery	None — assumes /dev/akida0 exists	Runtime sysfs scan, no hardcoded paths
Portability	Kernel module, Linux only	Rust crate, runs anywhere the hardware exists

---

Migration path

Before (C module + Python SDK):
  1. make && sudo insmod akida-pcie.ko
  2. sudo chmod 666 /dev/akida0
  3. python3 -c "import akida; model.map(); model(input)"

After (pure Rust):
  Option A — VFIO (no kernel module):
    akida bind-vfio 0000:a1:00.0      # once, requires root
    cargo run --bin enumerate          # no root

  Option B — kernel module fallback:
    sudo insmod akida-pcie.ko          # as before
    cargo run --bin enumerate          # Rust driver opens /dev/akida0

---

What the C module does (for reference)

akida-pcie-core.c implements a minimal PCIe driver that:

1. Registers with pci_register_driver for vendor 1e7c, device bca1
2. Calls pci_enable_device, pci_set_master, pci_request_regions
3. Wraps the DesignWare eDMA controller (dw_edma) for DMA transfers
4. Creates /dev/akida{N} character devices
5. Exposes read/write syscalls that trigger DMA

The Rust VFIO backend (rust/crates/akida-driver/src/vfio/mod.rs) replaces all of this with userspace equivalents via the Linux VFIO/IOMMU framework.