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Jefferson Gonçalves
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9front

#9front ARM64 — Orange Pi 4 Pro

Icon

Porting 9front to the Orange Pi 4 Pro (Allwinner A733).

#Quick Start

make help          # show available targets
make kernel        # build kernel (boots QEMU, compiles, extracts)
make sdcard        # build bootable SD card image

Flash to SD card:

sudo dd if=images/orangepi4pro/sdcard.img of=/dev/sdX bs=1M status=progress

#Build Targets

Target Description
make portdisk Pack port/a733/ into FAT image for QEMU transfer
make kernel Build kernel inside 9front QEMU (automated)
make sdcard Build bootable SD card image (64MB)
make boot Boot 9front QEMU (snapshot mode)
make dev Boot QEMU with port disk attached (interactive)
make serial-start Start tmux + picocom serial capture
make serial-fresh Truncate the serial log, then start capture
make serial-stop Stop tmux + picocom serial capture
make serial-status Show serial capture status
make serial-tail Tail the current serial log
make serial-attach Attach to the serial tmux session
make clean Remove build artifacts

#SD Card Image Layout

Offset Content
8 KiB boot0 — Allwinner SPL (loads U-Boot)
16.8 MiB boot_package — U-Boot + monitor + SCP firmware
32 MiB FAT32 partition — 9a733.u (kernel) + boot.scr

#Target Hardware
SoC Allwinner A733 (sun60iw2)
CPU 8-core ARM64 — 4× Cortex-A76 + 4× Cortex-A55
RAM 2/4/8/16 GB LPDDR
Storage eMMC, SD, PCIe (NVMe), USB 3.0
Network GbE (Synopsys GMAC), WiFi (AIC8800)
Display HDMI, eDP, DSI, LVDS
Console UART0 at 0x02500000 (ttyS0, 115200)

#Port Files

port/a733/
├── NOTES.md    # Hardware addresses, design decisions
├── a733        # Kernel config
├── bootargs.c  # Local DTB/bootargs handling override
├── clock.c     # Local ARM generic-timer override for bring-up sequencing
├── dat.h       # Data structures (from arm64/)
├── fns.h       # Function declarations and local wrapper prototypes
├── gic.c       # Local GICv3 mapping/bring-up override
├── io.h        # I/O and interrupt definitions
├── l.s         # Early boot assembly + UART breadcrumbs/wrappers
├── lcd.c       # Display init (WIP — inherits U-Boot framebuffer)
├── main.c      # Local early init override and bootstrap ordering
├── mem.c       # Local temporary MMU/map setup override
├── mem.h       # Memory map + A733 peripheral addresses
├── mkfile      # Build rules for local overrides
├── page.c      # Local page allocator instrumentation
├── pciaw.c     # PCIe host controller stub
├── proc.c      # Local scheduler/process instrumentation
├── screen.c    # Framebuffer console (WIP)
├── screen.h    # Screen declarations
├── trap.c      # Local trap/syscall/fault instrumentation
├── uartaw.c    # Allwinner UART driver (8250-compat, MMIO)
└── userinit.c  # Local first-process instrumentation

Shared arm64 code still reused from sys/src/9/arm64/ where not locally overridden: cache.v8.s, fpu.c, mmu.c, sysreg.c

#Development Workflow

  1. Edit files in port/a733/ on the host
  2. make portdisk — packs into FAT image
  3. make dev — boots QEMU with port disk attached
  4. Inside 9front: 
    dossrv -f /dev/sdG0/data portdisk
mount -c /srv/portdisk /n/port
dircp /n/port/a733 /sys/src/9/a733
cd /sys/src/9/a733 && mk
  5. Or: make kernel to automate steps 2–4 + extract

#Prerequisites

  • QEMU (qemu-system-aarch64)
  • mtools (mcopy, mformat, mdir)
  • expect (expect)
  • mkimage (u-boot-tools)
  • tmux + picocom (for make serial-* hardware logs)
  • qemu-user-static (for building vendor U-Boot boot blobs)
  • ARM cross-compiler (gcc-arm-linux-gnueabi, for vendor U-Boot only)

Pinned hardware bootstrap blobs are kept under bootstrap/orangepi4pro/. Generated outputs stay in images/<board>/.

#Peripheral Status

Peripheral Driver Status
GICv3 gic.c ✅ Local mapping/bring-up override
ARM Timer clock.c ✅ Local generic-timer override; IRQ timing still under bring-up
UART (serial) uartaw.c ✅ Written and used for breadcrumbs
Trap/syscall path trap.c 🔧 Instrumented for pid1 fault/syscall debugging
Scheduler/process path proc.c + userinit.c 🔧 Instrumented through first runnable process
PCIe pciaw.c 🔧 Stub (DesignWare init needed)
Framebuffer screen.c + lcd.c 🔧 Written, not yet in config
NVMe port/sdnvme.c ⏳ Needs PCIe
USB XHCI port/usbxhci.c ⏳ Needs testing
Ethernet — 🆕 Not started (Synopsys GMAC)
SD/eMMC — 🆕 Not started (Allwinner MMC)

#Current Bring-up Status

  • Raw boot chain is working: Boot0 → ATF → U-Boot → boot.scr
  • U-Boot accepts the Linux Image wrapper and DTB and reaches Starting kernel ...
  • The kernel now gets past the MMU transition, high-virtual handoff, main(), pageinit(), scheduler handoff, proc0(), init0(), and the first touser() edge
  • Latest captured breadcrumbs/log end after resolving pid1's first user stack write fault: 
    ...STZ5567890rspciaw...1234tuiI...JUvwxy[]...}kl...mnoABCDEFGHIpq
pid1 fault[0] ... far 0x3ffffefe90 write
pid1 fault[0] resolved
pid1 ureg preexit pc 0x10034 ... psr 0x80
  • Current work is focused on the first EL0 fault-return/syscall path for pid1, not boot media, DTB loading, serial capture, or the initial MMU enable

Detailed notes are in docs/BRINGUP-STATUS.md.

#Serial Monitoring

Default serial capture settings:

  • device: /dev/ttyUSB0
  • baud: 115200
  • tmux session: serial
  • log: /workspace/tmp/serial-boot.log

Use make serial-fresh, make serial-start, make serial-status, make serial-tail, make serial-attach, and make serial-stop.

#Repository Layout Convention

  • vendors/<name>/ — checked-out upstream source trees and submodules
  • bootstrap/<board>/ — checked-in board bootstrap binaries needed for hardware bring-up
  • images/<board>/ — board-specific generated images and emulator/runtime assets
  • port/a733/ — kernel port sources

#Vendor Resources

  • BSP: orangepi-xunlong/orangepi-build → local checkout at vendors/orangepi-build/
  • U-Boot fork: v2018.05-sun60iw2 branch on gitee
  • Board config: orangepi4pro.conf → sun60iw2 family
  • DTB: allwinner/sun60i-a733-orangepi-4-pro.dtb

Nouvelle version disponible.