Odroid-C2
 Please feel free to help us clean it up. |
(Parts of this page are WIP, still incomplete and some might be incorrect.)
Introduction
The Odroid-C2 single board computer is not very well supported by Alpine/Linux. However the "Generic ARM (aarch64)" build contains almost everything we need !
What do we need ?
- kernel : provided kernel by the Alpine team does not boot
- u-boot : provided u-boot does not autoboot without serial
- system files : everything is okay
On the hardware side:
- Odroid-C2
- Official PSU or just a micro-SD cable (notes : the barrel plug (inner(positive) diameter 0.8mm and outer(negative) diameter 2.5mm) is recommended, without the J1 jumper)
- micro-SD (or eMMC)
- USB to TTL (official or CP2102 chipset or an old rpi)
Required environement and toolchain
Using GNU/Linux is recommended and this guide and here are the required dependencies, for Debian (as example) :
apt install bc bison flex make gcc gcc-aarch64-linux-gnu libssl-dev libncurses-dev git squashfs-tools
We need to set specific environment variables IF you are not using an arm64 machine. Usually, you should be running on a x64 architecture (Intel or AMD I guess), so you would like to cross-compile.
export ARCH=arm64 export CROSS_COMPILE=aarch64-linux-gnu
Build u-boot from source
We need to build uboot from source as the u-boot provided does not autoboot without UART connected.
git clone --depth 1 https://source.denx.de/u-boot/u-boot.git -b v2022.01 u-boot-denx.de cd u-boot-denx.de export ARCH=arm64 && export CROSS_COMPILE=aarch64-linux-gnu- make mrproper && make odroid-c2_defconfig
We used the specific deconfig for the Odroid-C2 but, as mentionned before : we want to autoboot with or without UART connection. You can still access the SPL prompt by pressing the 'Enter' key twice before the two seconds countdown.
sed -i -e 's/.*CONFIG_SD_BOOT.*/CONFIG_SD_BOOT=y/' .config sed -i -e 's/.*CONFIG_AUTOBOOT_KEYED .*/CONFIG_AUTOBOOT_KEYED=y/' .config echo "CONFIG_AUTOBOOT_FLUSH_STDIN=y" >> .config echo "CONFIG_AUTOBOOT_PROMPT="Press quickly 'Enter' twice to stop autoboot: %d\n"" >> .config echo "# CONFIG_AUTOBOOT_ENCRYPTION is not set" >> .config echo "CONFIG_AUTOBOOT_DELAY_STR=""" >> .config echo "CONFIG_AUTOBOOT_STOP_STR="\xd\xd"" >> .config echo "CONFIG_AUTOBOOT_KEYED_CTRLC=y" >> .config
Then, it's time to build :
time make -j$(nproc)
Amlogic doesn’t provide sources for the firmware and for tools needed to create the bootloader image, so it is necessary to obtain them from the git tree published by the board vendor. Work in progress
Build the latest LTS kernel from source
git clone --depth 1 git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git -b linux-5.15.y linux-stable cd linux-stable export ARCH=arm64 && export CROSS_COMPILE=aarch64-linux-gnu- make mrproper && make defconfig
We need to adapt the default arm64 generated by defconfig. This configuration is required for Alpine/Linux and not enabled by default.
sed -i -e 's/.*CONFIG_SQUASHFS_XZ.*/CONFIG_SQUASHFS_XZ=y/' .config sed -i -e 's/.*CONFIG_UEVENT_HELPER.*/CONFIG_UEVENT_HELPER=y/' .config sed -i -e 's/.*CONFIG_BLK_DEV_RAM.*/CONFIG_BLK_DEV_RAM=y/' .config echo CONFIG_UEVENT_HELPER_PATH=\"/sbin/hotplug\" >> .config echo CONFIG_BLK_DEV_RAM_COUNT=16 >> .config echo CONFIG_BLK_DEV_RAM_SIZE=4096 >> .config
If you want to enable DVFS for the s905 amlogic cpu :
git apply --ignore-space-change --ignore-whitespace - << EOF
diff --git a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
index 201596247..027df3756 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
+++ b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
@@ -348,7 +348,8 @@ &saradc {
};
&scpi_clocks {
- status = "disabled";
+ /* Works only with new blobs that have limited DVFS table */
+ status = "okay";
};
/* SD */
EOF
</pe>
The, build your kernel, associated modules and the [https://elinux.org/Device_Tree_Reference#What_Is_Device_Tree DTB] (Device Tree Blob) from the source :
<pre>
time make -j$(nproc) Image dtbs modules
Create modloop:
rm -rf installed-modules && mkdir installed-modules INSTALL_MOD_PATH=installed-modules make modules_install find installed-modules -type l -delete rm -f modloop mksquashfs installed-modules/lib/ modloop -b 1048576 -comp xz -Xdict-size 100% -all-root rm -rf installed-modules
Assembly
Kernel part:
DST="/mnt/mmcblk0p1"
gzip -c arch/arm64/boot/Image > ${DST}/vmlinuz
cp .config ${DST}/config
cp modloop ${DST}/modloop
cp System.map ${DST}/System.map
Copy dtb:
mkdir ${DST}/boot/dtbs
cp arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts ${DST}/boot/dtbs
cp arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dtb ${DST}/boot/dtbs
System part:
Work in progress
Booting
Work in progress
Troubleshooting
Work in progress