N94 Linux

Experimental Linux 6.6 bring-up for the Apple iPhone 4S (iPhone4,1, N94AP, S5L8940X). The current development chain reaches an ARMv7 Alpine userspace on physical hardware and can expose USB serial, USB Ethernet, and SSH.

This repository contains source code and reproducible patches only. It does not contain Apple firmware, decrypted boot components, IPSW files, jailbreak payloads, device dumps, credentials, or prebuilt operating-system images.

Hardware status

Component	Status
ARMv7 kernel entry and paging	Working on hardware
Linux 6.6 userspace / PID 1	Working on hardware
Simple framebuffer and fbcon	Working on hardware
Alpine ARMv7 initramfs	Working on hardware
Xorg fbdev and XFCE userspace	Starts on hardware; no GPU acceleration
Clocksource and clockevent	Working with the current polling implementation
Apple AIC interrupt dispatch	Working for the tested USB path
Synopsys DWC2 peripheral mode	Working on hardware
CDC ACM serial	Working on hardware
CDC ECM Ethernet and SSH	Working on hardware
Multitouch	Not implemented
NAND/root filesystem	Not implemented
Wi-Fi, audio, battery, charging	Not implemented
GPU acceleration	Not available
Persistent or device-only boot	Not implemented or published

The verified workflow is a host-assisted, volatile RAM boot. It does not modify NAND and is not a dual-boot installer.

Repository layout

• patches/linux-6.6-n94.patch — changes against upstream Linux 6.6.
• configs/n94.config — configuration used for the current bring-up kernel.
• boot/ — ARM stages, image headers, linker scripts, and N94 device tree.
• rootfs/minimal/ — minimal no-libc PID 1 source and initramfs manifest.
• rootfs/alpine/ — Alpine ARMv7/Xorg/XFCE rootfs builder.
• tools/ — image packer and read-only Apple DeviceTree/PMGR inspection tools.
• docs/ — build, hardware, status, and contribution notes.

Build overview

1. Obtain Linux 6.6 from an official kernel source.
2. Apply patches/linux-6.6-n94.patch.
3. Copy configs/n94.config to the kernel tree as .config and select an initramfs source appropriate for the intended test.
4. Build an ARMv7 zImage with a suitable cross compiler.
5. Use tools/n94_pack.py to assemble the N94 boot bundle.

See docs/BUILD.md for the expected directory layout and verification steps. The boot procedure intentionally omits redistribution of Apple components; researchers must obtain any required firmware lawfully from their own device or Apple-provided restore image.

Safety and scope

This is early hardware-enablement work. A failed RAM boot should be recoverable through DFU, but experimental boot code can hang the device and may cause data loss if extended to storage writes. The published code does not require or perform persistent boot configuration changes.

License

The project is licensed under GPL-2.0-only. Linux-derived files remain subject to the Linux kernel's license and copyright notices. Third-party projects are not vendored; see NOTICE.md.