secubox-deb/wiki/Netboot-Install.md

Netboot Install — MOCHAbin from gk2

Network-boot a second MOCHAbin (c3box) from gk2's netboot rig and perform a fully automated, cryptographically verified SecuBox Debian install to eMMC.

Validated 2026-06-27 (factory U-Boot 2020.10, custom kernel 6.12.85 #5secubox, image secubox-mochabin-bookworm CI run 27426515472).

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Prerequisites

Item	Detail
Cable	Straight copper RJ45 from gk2 lan1 to c3box mvpp2-2 (the single copper port, not the 4-port switch)
Signing key	secubox-netboot.key on gk2 (matches netboot-image.pub embedded in the installer FIT)
Image	secubox-mochabin-bookworm artifact from CI (latest successful build-packages + build-image run)
gk2 services	dnsmasq DHCP on 192.168.77.0/24, TFTP root /srv/tftp, nginx :8099 serving signed image
Serial console	USB-UART to c3box debug header (115200 8N1) to catch factory U-Boot

Port note: Only mvpp2-2 (the single copper RJ45) is reachable by the factory U-Boot. The 4 switch ports require the MV88E6XXX DSA driver which is absent at early boot.

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Step 1 — Publish the signed image on gk2

# Sign the image
openssl dgst -sha256 -sign /etc/secubox/netboot/secubox-netboot.key \
  -out /srv/netboot/sbx.img.gz.sig /data/sbx.img.gz

# Publish (symlink or copy into the nginx root)
ln -sf /data/sbx.img.gz /srv/netboot/sbx.img.gz
ln -sf /data/sbx.img.gz.sig /srv/netboot/sbx.img.gz.sig

# Verify the public key matches what the installer FIT embeds
openssl rsa -in /etc/secubox/netboot/secubox-netboot.key -pubout \
  | diff - /etc/secubox/netboot/netboot-image.pub

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Step 2 — Catch the factory U-Boot on c3box

Power-cycle c3box. On the serial console you have 2 seconds (bootdelay=2).

Important: press Enter to interrupt autoboot — NOT Ctrl-C.

Hit any key to stop autoboot:  2
Marvell>> 

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Step 3 — Configure TFTP environment

# Set TFTP block size for fast transfer
setenv tftpblocksize 1468

# Set the TFTP server (gk2 lan1 address)
setenv serverip 192.168.77.1
setenv ipaddr 192.168.77.100

# Save (optional — env is NOT in SPI mtd2 on this board, lost on power cycle)
# saveenv

U-Boot env note: fw_setenv from Linux has no effect on this board — the factory U-Boot does not store its env in SPI mtd2 (a stale foreign env sits there). All env changes must be made interactively in the U-Boot shell.

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Step 4 — Load installer via TFTP and boot

# Load kernel, DTB, initrd into free RAM addresses (NOT 0x02080000 — reserved)
tftpboot 0x0a000000 Image
tftpboot 0x09000000 armada-7040-mochabin.dtb
tftpboot 0x10000000 initrd.img

# Boot
booti 0x0a000000 0x10000000 0x09000000

The installer rescue shell appears. The 49 MB signed FIT is fetched automatically from http://192.168.77.1:8099/ during installer init.

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Step 5 — Automated verified install from the rescue shell

# Download image to RAM (c3box has 8 GB — fits comfortably)
wget http://192.168.77.1:8099/sbx.img.gz -O /tmp/sbx.img.gz
wget http://192.168.77.1:8099/sbx.img.gz.sig -O /tmp/sbx.img.gz.sig

# Verify signature against the embedded public key
openssl dgst -sha256 -verify /etc/secubox/installer/netboot-image.pub \
  -signature /tmp/sbx.img.gz.sig /tmp/sbx.img.gz
# Expected output: Verified OK

# Stream to eMMC (progress tracked via status=progress)
gunzip -c /tmp/sbx.img.gz | dd of=/dev/mmcblk0 bs=4M conv=fsync status=progress
sync

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Step 6 — Fix auto-boot persistence (boot.scr)

The image ships extlinux.conf pointing to 0x02080000 (reserved on factory U-Boot — causes an immediate reset). It also ships no compiled boot.scr. Build one before rebooting:

# From the rescue shell, after dd completes, mount the boot partition
mount /dev/mmcblk0p1 /mnt

cat > /tmp/boot.cmd << 'EOF'
setenv bootargs "console=ttyS0,115200 earlycon root=LABEL=rootfs rw"
load mmc 0:1 0x0a000000 Image
load mmc 0:1 0x10000000 initrd.img
load mmc 0:1 0x09000000 armada-7040-mochabin.dtb
booti 0x0a000000 0x10000000:${filesize} 0x09000000
EOF

mkimage -C none -A arm64 -T script -d /tmp/boot.cmd /mnt/boot.scr
sync
umount /mnt

Reboot. The factory U-Boot picks up boot.scr from mmc and boots Debian unattended.

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Gotchas

Symptom	Root cause	Fix
Board resets immediately after kernel load	Kernel loaded at 0x02080000 (reserved memory region)	Use 0x0a000000 for kernel, 0x10000000 for initrd
TFTP very slow	Default block size too small	setenv tftpblocksize 1468
fw_setenv from Linux has no effect	Factory U-Boot env is NOT in SPI mtd2 (stale foreign env there)	Reconfigure U-Boot env interactively each time, or use boot.scr
Autoboot not interrupted	Interrupt key is Enter, not Ctrl-C	Press Enter within 2 seconds of power-on
Switch ports (4-port block) unreachable at boot	MV88E6XXX DSA driver absent in factory U-Boot	Cable must go to mvpp2-2 (single copper RJ45)
Image boots but SecuBox stack not starting	First boot — wait ~90 s for systemd units to settle	Check journalctl -u secubox-aggregator

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eMMC layout after install

Partition	Type	Mount	Purpose
mmcblk0p1	FAT32	/boot	Kernel, DTB, initrd, boot.scr, extlinux.conf
mmcblk0p2	ext4	/	Root filesystem
mmcblk0p3	ext4	/data	Persistent data

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Related

• ARM-Installation — general ARM installation guide
• Hardware-Matrix — board support matrix
• feature/748-enhanced-tow-boot-http-netboot-serial-fl — enhanced Tow-Boot with native HTTP/wget (blocked, see #748)
• GitHub: #748 · #737