🛠 Installer le système sur l'eMMC : rkdeveloptool, MaskROM et gain de fiabilité

Objectives

SKUs with onboard eMMC feature soldered 5.1 memory (8/16/32/64 GB, no socket: capacity is fixed at purchase) configured in 8-bit HS200 (mmc-hs200-1_8v, non-removable in the mainline device tree). Installing the system on eMMC rather than a microSD card provides robustness (no moving contacts) and often higher speed. Two methods are covered: from a system booting on SD using rkdeveloptool, and via Rockusb mode (MaskROM button + USB-C 1) from a PC.

Hardware

• 1 Radxa ZERO 3W with eMMC (check your SKU!)
• 1 microSD card with a functional Radxa OS (method 1)
• 1 Linux PC with rkdeveloptool installed (sudo apt install rkdeveloptool) (method 2)
• 1 USB-C data cable (not a charge-only cable)
• The .img file to install (same file as in an SD flash tutorial)

Method 1 — From the system booted on SD

# La carte voit-elle son eMMC ?
lsblk            # sda/mmcblk1 pour la SD, mmcblk2 (ou mmcblk1) pour l'eMMC
sudo fdisk -l    # identifiez bien le périphérique eMMC AVANT d'écrire

# Copie directe image -> eMMC (ATTENTION : efface tout l'eMMC)
sudo unxz -k radxa-zero3_bookworm_kde_b1.img.xz
sudo dd if=radxa-zero3_bookworm_kde_b1.img of=/dev/mmcblk2 bs=4M status=progress conv=fsync
sudo sync && sudo poweroff

Then remove the microSD card: the boot order microSD → eMMC → USB automatically switches to eMMC.

Method 2 — Rockusb from the PC (card "empty")

# 1. Carte éteinte : maintenir le bouton MaskROM, brancher USB-C 1 vers le PC,
#    relâcher. Le contrôleur RK3566 apparaît en mode téléchargement.
lsusb | grep -i rockchip          # id 2207:350x
sudo rkdeveloptool ld              # liste la mémoire (BootROM/eMMC détectés)
sudo rkdeveloptool wl 0 radxa-zero3_bookworm_kde_b1.img   # écrit l'image à 0
sudo rkdeveloptool rd              # redémarre la carte

Radxa also documents the Rockchip "factory upgrade tool" (Rockchip Batch/Android Tool) as a graphical alternative; the official low-level-dev flow describes rkdeveloptool.

Expected verification

lsblk -o NAME,MODEL,SIZE,ROTA shows the root system on the eMMC device (root=PARTUUID... on mmcblk2). A rough speed test: sudo hdparm -Tt /dev/mmcblk2 or dd if=/dev/zero of=test bs=1M count=512 oflag=direct — HS200 eMMC typically outperforms a class 10 SD card in sequential/4K access. dmesg | grep mmc confirms the HS200 8-bit negotiation.

Common errors

• Writing to the wrong device: with SD + eMMC simultaneously present, mmcblk indices can swap depending on the kernel — check the size (lsblk) before each dd.
• Believing the eMMC is removable: it is soldered onto production boards; you cannot "change the OS card" by swapping a chip.
• Using a charge-only USB-C cable in MaskROM mode: lsusb shows nothing — test with a known data cable.
• Forgetting to release/hold the MaskROM button at the right timing: plugging in without holding the button causes the board to boot normally instead of entering Rockusb.
• Powering the board from another source during eMMC writing: keep it powered solely by the PC's USB port to avoid interruptions mid-write.
• Not syncing before powering off: corrupted eMMC system; the dd command above includes conv=fsync, followed by an explicit sync.
• Full eMMC: 8 GB on smaller SKUs — a full desktop image + apt full-upgrade can saturate it; plan for a server image or a more generous SKU.