initial buildroot for linux 5.15

board/raspberrypi/config_0w.txt

@@ -0,0 +1,29 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on

board/raspberrypi/config_3.txt

@@ -0,0 +1,29 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on

board/raspberrypi/config_3_64bit.txt

@@ -0,0 +1,32 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=Image
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on
+
+# enable 64bits support
+arm_64bit=1

board/raspberrypi/config_3_qt5we.txt

@@ -0,0 +1,26 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=200
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt

board/raspberrypi/config_4.txt

@@ -0,0 +1,29 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start4.elf
+fixup_file=fixup4.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on

board/raspberrypi/config_4_64bit.txt

@@ -0,0 +1,36 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start4.elf
+fixup_file=fixup4.dat
+
+kernel=Image
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable autoprobing of Bluetooth driver without need of hciattach/btattach
+dtoverlay=krnbt=on
+
+dtoverlay=vc4-kms-v3d-pi4
+dtoverlay=imx219
+#dtoverlay=ov5647
+
+# enable 64bits support
+arm_64bit=1

board/raspberrypi/config_cm4io.txt

@@ -0,0 +1,26 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start4.elf
+fixup_file=fixup4.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt

board/raspberrypi/config_cm4io_64bit.txt

@@ -0,0 +1,30 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start4.elf
+fixup_file=fixup4.dat
+
+kernel=Image
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100
+
+# fixes rpi (3B, 3B+, 3A+, 4B and Zero W) ttyAMA0 serial console
+dtoverlay=miniuart-bt
+
+# enable 64bits support
+arm_64bit=1
+

board/raspberrypi/config_default.txt

@@ -0,0 +1,23 @@
+# Please note that this is only a sample, we recommend you to change it to fit
+# your needs.
+# You should override this file using BR2_PACKAGE_RPI_FIRMWARE_CONFIG_FILE.
+# See http://buildroot.org/manual.html#rootfs-custom
+# and http://elinux.org/RPiconfig for a description of config.txt syntax
+
+start_file=start.elf
+fixup_file=fixup.dat
+
+kernel=zImage
+
+# To use an external initramfs file
+#initramfs rootfs.cpio.gz
+
+# Disable overscan assuming the display supports displaying the full resolution
+# If the text shown on the screen disappears off the edge, comment this out
+disable_overscan=1
+
+# How much memory in MB to assign to the GPU on Pi models having
+# 256, 512 or 1024 MB total memory
+gpu_mem_256=100
+gpu_mem_512=100
+gpu_mem_1024=100

board/raspberrypi/genimage-raspberrypi.cfg

@@ -0,0 +1,33 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2708-rpi-b.dtb",
+			"bcm2708-rpi-b-plus.dtb",
+			"bcm2708-rpi-cm.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi0.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2708-rpi-zero.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi0w.cfg

@@ -0,0 +1,32 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2708-rpi-zero-w.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"rpi-firmware/overlays",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi2.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2709-rpi-2-b.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi3-64.cfg

@@ -0,0 +1,34 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2710-rpi-3-b.dtb",
+			"bcm2710-rpi-3-b-plus.dtb",
+			"bcm2837-rpi-3-b.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"rpi-firmware/overlays",
+			"Image"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi3.cfg

@@ -0,0 +1,34 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2710-rpi-3-b.dtb",
+			"bcm2710-rpi-3-b-plus.dtb",
+			"bcm2710-rpi-cm3.dtb",
+			"rpi-firmware/bootcode.bin",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup.dat",
+			"rpi-firmware/start.elf",
+			"rpi-firmware/overlays",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi4-64.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2711-rpi-4-b.dtb",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup4.dat",
+			"rpi-firmware/start4.elf",
+			"rpi-firmware/overlays",
+			"Image"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypi4.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2711-rpi-4-b.dtb",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup4.dat",
+			"rpi-firmware/start4.elf",
+			"rpi-firmware/overlays",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypicm4io-64.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2711-rpi-cm4.dtb",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup4.dat",
+			"rpi-firmware/start4.elf",
+			"rpi-firmware/overlays",
+			"Image"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/genimage-raspberrypicm4io.cfg

@@ -0,0 +1,31 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"bcm2711-rpi-cm4.dtb",
+			"rpi-firmware/cmdline.txt",
+			"rpi-firmware/config.txt",
+			"rpi-firmware/fixup4.dat",
+			"rpi-firmware/start4.elf",
+			"rpi-firmware/overlays",
+			"zImage"
+		}
+	}
+
+	size = 32M
+}
+
+image sdcard.img {
+	hdimage {
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/raspberrypi/post-build.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -u
+set -e
+
+# Add a console on tty1
+if [ -e ${TARGET_DIR}/etc/inittab ]; then
+    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
+	sed -i '/GENERIC_SERIAL/a\
+tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
+fi

board/raspberrypi/post-image.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+
+set -e
+
+BOARD_DIR="$(dirname $0)"
+BOARD_NAME="$(basename ${BOARD_DIR})"
+GENIMAGE_CFG="${BOARD_DIR}/genimage-${BOARD_NAME}.cfg"
+GENIMAGE_TMP="${BUILD_DIR}/genimage.tmp"
+
+# Pass an empty rootpath. genimage makes a full copy of the given rootpath to
+# ${GENIMAGE_TMP}/root so passing TARGET_DIR would be a waste of time and disk
+# space. We don't rely on genimage to build the rootfs image, just to insert a
+# pre-built one in the disk image.
+
+trap 'rm -rf "${ROOTPATH_TMP}"' EXIT
+ROOTPATH_TMP="$(mktemp -d)"
+
+rm -rf "${GENIMAGE_TMP}"
+
+genimage \
+	--rootpath "${ROOTPATH_TMP}"   \
+	--tmppath "${GENIMAGE_TMP}"    \
+	--inputpath "${BINARIES_DIR}"  \
+	--outputpath "${BINARIES_DIR}" \
+	--config "${GENIMAGE_CFG}"
+
+exit $?

board/raspberrypi/readme.txt

@@ -0,0 +1,148 @@
+Raspberry Pi
+
+Intro
+=====
+
+These instructions apply to all models of the Raspberry Pi:
+  - the original models A and B,
+  - the "enhanced" models A+ and B+,
+  - the model B2 (aka Raspberry Pi 2)
+  - the model B3 (aka Raspberry Pi 3).
+  - the model B4 (aka Raspberry Pi 4).
+  - the model CM4 (aka Raspberry Pi Compute Module 4 and IO Board).
+
+How to build it
+===============
+
+Configure Buildroot
+-------------------
+
+There are two RaspberryPi defconfig files in Buildroot, one for each
+major variant, which you should base your work on:
+
+For models A, B, A+ or B+:
+
+  $ make raspberrypi_defconfig
+
+For model Zero (model A+ in smaller form factor):
+
+  $ make raspberrypi0_defconfig
+
+For model 2 B:
+
+  $ make raspberrypi2_defconfig
+
+For model 3 B and B+:
+
+  $ make raspberrypi3_defconfig
+
+or for model 3 B and B+ (64 bit):
+
+  $ make raspberrypi3_64_defconfig
+
+For model 4 B:
+
+  $ make raspberrypi4_defconfig
+
+or for model 4 B (64 bit):
+
+  $ make raspberrypi4_64_defconfig
+
+For model CM4 (on IO Board):
+
+  $ make raspberrypicm4io_defconfig
+
+or for CM4 (on IO Board - 64 bit):
+
+  $ make raspberrypicm4io_64_defconfig
+
+Build the rootfs
+----------------
+
+Note: you will need to have access to the network, since Buildroot will
+download the packages' sources.
+
+You may now build your rootfs with:
+
+  $ make
+
+(This may take a while, consider getting yourself a coffee ;-) )
+
+Result of the build
+-------------------
+
+After building, you should obtain this tree:
+
+    output/images/
+    +-- bcm2708-rpi-b.dtb           [1]
+    +-- bcm2708-rpi-b-plus.dtb      [1]
+    +-- bcm2709-rpi-2-b.dtb         [1]
+    +-- bcm2710-rpi-3-b.dtb         [1]
+    +-- bcm2710-rpi-3-b-plus.dtb    [1]
+    +-- bcm2711-rpi-4-b.dtb         [1]
+    +-- bcm2711-rpi-cm4.dtb         [1]
+    +-- boot.vfat
+    +-- rootfs.ext4
+    +-- rpi-firmware/
+    |   +-- bootcode.bin
+    |   +-- cmdline.txt
+    |   +-- config.txt
+    |   +-- fixup.dat               [1]
+    |   +-- fixup4.dat              [1]
+    |   +-- start.elf               [1]
+    |   +-- start4.elf              [1]
+    |   `-- overlays/               [2]
+    +-- sdcard.img
+    +-- Image                       [1]
+    `-- zImage                      [1]
+
+[1] Not all of them will be present, depending on the RaspberryPi
+    model you are using.
+
+[2] Only for the Raspberry Pi 3/4 Models (overlay miniuart-bt is needed
+    to enable the RPi3 serial console otherwise occupied by the bluetooth
+    chip). Alternative would be to disable the serial console in cmdline.txt
+    and /etc/inittab.
+
+How to write the SD card
+========================
+
+Once the build process is finished you will have an image called "sdcard.img"
+in the output/images/ directory.
+
+Copy the bootable "sdcard.img" onto an SD card with "dd":
+
+  $ sudo dd if=output/images/sdcard.img of=/dev/sdX
+
+Insert the SDcard into your Raspberry Pi, and power it up. Your new system
+should come up now and start two consoles: one on the serial port on
+the P1 header, one on the HDMI output where you can login using a USB
+keyboard.
+
+How to write to CM4 eMMC memory
+===============================
+
+For CM4 modules without eMMC memory see above for booting from SD card,
+for CM4 moduels with eMMC memory proceed as following:
+
+- fit jumper on IO Board header J2 to disable eMMC boot
+- connect IO Board micro USB port (J11 USB slave) to your host linux system
+- power up CM4/IO Board (lsusb command should show a '0a5c:2711 Broadcom Corp.
+  BCM2711 Boot' device)
+- run 'sudo ./host/bin/rpiboot', output should look like the following:
+    Waiting for BCM2835/6/7/2711...
+    Loading embedded: bootcode4.bin
+    Sending bootcode.bin
+    Successful read 4 bytes
+    Waiting for BCM2835/6/7/2711...
+    Loading embedded: bootcode4.bin
+    Second stage boot server
+    Loading embedded: start4.elf
+    File read: start4.elf
+    Second stage boot server done
+
+- a USB mass storage device should show up (the CM4 eMMC memory), proceed
+  as described above to copy sdcard.img to it
+- power down CM4/IO Board
+- remove jumper on IO Board header J2 to re-enable eMMC boot
+- power up CM4/IO Board