228 lines
No EOL
6.9 KiB
Markdown
228 lines
No EOL
6.9 KiB
Markdown
# eMMC Multi-Boot Setup — Orange Pi 3B
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**Status:** Procedural reference. Last verified: 2026-06-02 (discussion with Jez).
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## Goal
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Boot multiple ARM64 OSes from the OPi 3B's onboard 256GB eMMC, with a u-boot boot menu (`extlinux.conf`) appearing at power-on. No SD card needed after setup.
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**Planned OSes:** Orange Pi OS (Arch), Armbian, NixOS
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SPI NOR flash was erased via maskrom and is unused going forward.
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## Boot Chain (after SPI erase)
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```
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BootROM → SPI (empty, skip) → microSD (if inserted) → eMMC boot partition → extlinux.conf → menu → kernel
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```
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If microSD **is** inserted and has a valid bootloader, it takes priority over eMMC. Useful as a lifeboat/rescue path — if eMMC boot breaks, pop in the SD card and you're back.
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## Partition Layout
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Proposed new partition schema:
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```
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mmcblk1 (256GB eMMC)
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├── mmcblk1boot0 (hardware boot partition — u-boot SPL + proper)
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├── mmcblk1boot1 (unused mirror)
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└── mmcblk1
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├── mmcblk1p1 FAT32 1GB /boot (extlinux.conf, kernels, DTBs — shared)
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├── mmcblk1p2 ext4 85GB root_opios (Orange Pi OS Arch)
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├── mmcblk1p3 ext4 85GB root_armbian (Armbian)
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└── mmcblk1p4 ext4 ~84GB root_nixos (NixOS)
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```
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### Why a dedicated FAT32 boot partition?
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u-boot reads `extlinux.conf` from a FAT, ext4, or btrfs partition. FAT32 is the most universally supported across distro kernel packages. A shared `/boot` means all three OSes drop their kernels and DTBs into one place, and a single `extlinux.conf` controls the menu. 1GB gives headroom for multiple kernel versions across all three OSes.
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## Step 1: Clone SD → eMMC
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Move Orange Pi OS from the microSD card to eMMC and leave two more root paritions ready for other operating systems later.
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### 1.1 — Identify devices
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Run on the running Orange Pi OS (booted from SD):
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```bash
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lsblk
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mount | grep mmcblk
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```
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Expected:
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- `mmcblk0` = SD card (current boot device)
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- `mmcblk1` = eMMC (target boot device)
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Actual:
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- `mmcblk0` = eMMC (target boot device)
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- `mmcblk1` = SD card (current boot device)
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Ground truth state with only OPi OS on SD card:
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```bash
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[jez@Rocky ~]$ lsblk
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NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
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mtdblock0 31:0 0 16M 0 disk
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mmcblk0 179:0 0 233G 0 disk
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mmcblk0boot0 179:32 0 4M 1 disk
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mmcblk0boot1 179:64 0 4M 1 disk
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mmcblk1 179:96 0 238.4G 0 disk
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├─mmcblk1p1 179:97 0 213.6M 0 part /boot
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└─mmcblk1p2 179:98 0 238.2G 0 part /
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zram0 254:0 0 0B 0 disk
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```
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### 1.2 — Wipe eMMC partition table
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**Destroys everything on eMMC.** Skip if eMMC is already empty.
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```bash
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sudo sgdisk --zap-all /dev/mmcblk0
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sudo blkdiscard /dev/mmcblk0 # optional
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```
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### 1.3 — Partition eMMC
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```bash
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sudo gdisk /dev/mmcblk0
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```
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In `gdisk` interactive mode:
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```
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o (new GPT)
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n 1 default +1G ef00 name=boot
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n 2 default +85G 8300 name=root_opios
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n 3 default +85G 8300 name=root_armbian
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n 4 default default 8300 name=root_nixos
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w (write, confirm 'y')
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```
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### 1.4 — Create filesystems
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```bash
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sudo mkfs.vfat -F 32 -n BOOT /dev/mmcblk0p1
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sudo mkfs.ext4 -L root_opios /dev/mmcblk0p2
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sudo mkfs.ext4 -L root_armbian /dev/mmcblk0p3
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sudo mkfs.ext4 -L root_nixos /dev/mmcblk0p4
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```
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### 1.5 — Mount and rsync the live rootfs
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```bash
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sudo mkdir -p /mnt/root_opios
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sudo mount /dev/mmcblk0p2 /mnt/root_opios
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sudo mkdir -p /mnt/root_opios/boot
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sudo mount /dev/mmcblk0p1 /mnt/root_opios/boot
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sudo rsync -axHAWX --info=progress2 / /mnt/root_opios/
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sudo rsync -aHAWX /boot/ /mnt/root_opios/boot/ # /boot is a separate partition, -x skips it
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```
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Flags: archive, stay-on-filesystem (critical — skips /proc, /sys, /dev), preserve
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hardlinks/ACLs/xattrs, copy whole files (faster locally). The second rsync handles the
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separate /boot partition that -x deliberately avoids.
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### 1.6 — Bind mount virtual filesystems
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```bash
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sudo mkdir -p /mnt/root_opios/{proc,sys,dev,run,tmp}
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sudo mount --bind /proc /mnt/root_opios/proc
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sudo mount --bind /sys /mnt/root_opios/sys
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sudo mount --bind /dev /mnt/root_opios/dev
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sudo mount --bind /run /mnt/root_opios/run
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```
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### 1.7 — Update fstab
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```bash
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sudo blkid /dev/mmcblk0p1 /dev/mmcblk0p2
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```
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Edit `/mnt/root_opios/etc/fstab`. Replace old SD card references with:
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```
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UUID=<boot-UUID> /boot vfat defaults,noatime 0 2
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UUID=<root_opios-UUID> / ext4 defaults,noatime 0 1
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```
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### 1.8 — Write extlinux.conf
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```bash
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uname -r
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find /mnt/root_opios/boot -name "*.dtb" | grep orangepi-3b
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```
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Create `/mnt/root_opios/boot/extlinux/extlinux.conf`:
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```
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TIMEOUT 10
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DEFAULT orangepi-os
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LABEL orangepi-os
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MENU LABEL Orange Pi OS
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LINUX /vmlinuz-<kernel-version>
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INITRD /initrd.img-<kernel-version>
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FDT /dtbs/rockchip/rk3566-orangepi-3b.dtb
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APPEND root=UUID=<root_opios-UUID> rootwait console=ttyS2,115200 console=tty1
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```
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### 1.9 — Install u-boot to eMMC hardware boot partition
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First check if Orange Pi OS ships u-boot binaries:
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```bash
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find / -name "idbloader.img" -o -name "u-boot.itb" -o -name "*loader*" 2>/dev/null
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```
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If files exist at known paths, use them. If not, extract from SD card. The idbloader
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starts at sector 64 of the SD card (sectors 0-33 hold the GPT), so skip there:
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```bash
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sudo dd if=/dev/mmcblk1 of=idbloader.img bs=512 skip=64 count=16320
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sudo dd if=/dev/mmcblk1 of=u-boot.itb bs=512 skip=16384 count=8192
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```
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Write to eMMC hardware boot partition:
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```bash
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echo 0 | sudo tee /sys/block/mmcblk0/force_ro
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sudo mmc bootpart enable 1 1 /dev/mmcblk0
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sudo dd if=idbloader.img of=/dev/mmcblk0boot0 bs=512 seek=64
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sudo dd if=u-boot.itb of=/dev/mmcblk0boot0 bs=512 seek=16384
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sudo sync
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```
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### 1.10 — Clean up and test
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```bash
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sudo umount /mnt/root_opios/boot
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sudo umount /mnt/root_opios/proc /mnt/root_opios/sys /mnt/root_opios/dev /mnt/root_opios/run
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sudo umount /mnt/root_opios
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sudo sync
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sudo poweroff
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```
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Remove SD card. Power on. u-boot logo → boot menu → Orange Pi OS from eMMC.
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### Troubleshooting
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| Symptom | Likely cause | Fix |
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| u-boot logo, then blank screen | EDID/HDMI handshake | Add `video=HDMI-A-1:1920x1080@60e` to APPEND line |
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| "No bootable device" | u-boot not written to eMMC boot part | Re-do step 1.9 |
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| Kernel panic: can't find root | Wrong UUID in extlinux.conf | Boot from SD, mount eMMC, fix UUID |
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| Nothing on screen at all | SPI flash interference? HDMI? | Re-check SPI erase, try different monitor |
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## Step 2: Install Armbian
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(To be documented — Armbian rootfs goes into root_armbian, kernel+DTB added to shared /boot, next LABEL added to extlinux.conf.)
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## Step 3: Install NixOS
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(To be documented — NixOS rootfs goes into root_nixos. Likely the trickiest since NixOS generates its own /boot structure.)
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## Reference
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- Rockchip boot flow: <https://opensource.rock-chips.com/wiki_Boot_option>
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- U-boot extlinux format: <https://docs.u-boot.org/en/stable/develop/distro.html>
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- OPi 3B bring-up: `docs/initial-bringup.md`
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- Storage architecture: `docs/storage-architecture.md` |