This page describes how to set up Baserock running natively on the Acer CB5-311 Chromebook. Although Baserock can be installed onto the internal SSD, it is recommended to use an external HDD or SD card because the internal space is limited and dual boot with Chrome OS is convenient for developers.
Please be aware to check the devices e.g. with lsblk every time before running commands like dd and replace where appropriate.
Chrome OS Developer Mode
To activate the developer mode, hold down the ESC and Refresh (F3) keys and poke the Power button. During booting press one of the following:
Ctrl-D # Chrome OS dev mode
Ctrl-U # USB boot
Boot into Chrome OS dev mode, press Alt+Ctrl+T and type:
# Will jump into shell
shell
Enable legacy and USB/SD boot (crossystem man page can be found here)
sudo crossystem dev_boot_usb=1
Configuration of crossystem has to been repeated after an automatic Update of Chrome OS.
Partitioning
On your desktop machine, attach a USB HDD and do the following:
# Install packages needed to partition and sign, e.g. on Ubuntu
apt-get install cgpt vboot-kernel-utils
# Partitioning the device, Kernel partition and two 100GB btrfs (size in 512 Byte blocks)
parted --script /dev/sdX mklabel gpt
cgpt create /dev/sdX
cgpt add -t kernel -l uboot/kernel -b 34 -s 16384 /dev/sdX
cgpt add -t data -l / -b 16418 -s 195300000 /dev/sdX
cgpt add -t data -l / -b 195316418 -s 195300000 /dev/sdX
blockdev --rereadpt /dev/sdX
# Create the root filesystem
mkfs.btrfs /dev/sdX2
mkfs.btrfs /dev/sdX3
# Mount partition
mkdir /mnt/rootfs
mount /dev/sdX2 /mnt/rootfs/
# Create rootfs subvolume
cd /mnt/rootfs
mkdir -p system/factory
btrfs subvolume create system/factory/run
ln -sv system/factory system/default
umount /mnt/rootfs
# Mount the subvolume
mount -o subvol=system/factory/run /dev/sdX2 /mnt/rootfs/
# Get a plain ARM Baserock rootfs and extract
mkdir ~/baserock_rootfs
cd ~/baserock_rootfs
wget http://download.baserock.org/baserock/build-system-armv7lhf-rootfs.tar.gz
tar xvf build-system-armv7lhf-rootfs.tar.gz -C /mnt/rootfs
Build the Kernel
Build the Kernel from the repository (>=4.8 of arm-linux-gnueabi-gcc is needed)
cd ~/
git clone https://chromium.googlesource.com/chromiumos/third_party/kernel
cd kernel
git checkout chromeos-3.10
./chromeos/scripts/prepareconfig chromeos-tegra
./scripts/config -e CONFIG_FRAMEBUFFER_CONSOLE
./scripts/config -m CONFIG_USB_NET_CDC_MBIM
./scripts/config --set-val CONFIG_EXTRA_FIRMWARE \"nvidia/tegra124/xusb.bin\"
./scripts/config --set-val CONFIG_EXTRA_FIRMWARE_DIR \"/mnt/rootfs/lib/firmware\"
./scripts/config -m CONFIG_VLAN_8021Q
./scripts/config -e CONFIG_VT
./scripts/config -e CONFIG_VT_CONSOLE
# Enable BTRFS support
./scripts/config -e BTRFS_FS
# Download the USB firmware binary
wget http://commondatastorage.googleapis.com/chromeos-localmirror/distfiles/xhci-firmware-2014.10.10.00.00.tbz2
tar xvf xhci-firmware-2014.10.10.00.00.tbz2 -C /mnt/rootfs/
# Build .config, Kernel, modules and install them
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- oldnoconfig WIFIVERSION=-3.8
make -j2 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- -k zImage tegra124-nyan-big.dtb modules WIFIVERSION=-3.8
# Install the Kernel modules
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- INSTALL_PATH=/mnt/rootfs/boot INSTALL_MOD_PATH=/mnt/rootfs firmware_install modules_install WIFIVERSION=-3.8
Create an its_script.its for mkimage (more information in the Chrome OS SDK Kernel ebuild):
/dts-v1/;
/ {
description = "Chrome OS kernel image with one or more FDT blobs";
#address-cells = <1>;
images {
kernel@1 {
data = /incbin/("./arch/arm/boot/zImage");
type = "kernel_noload";
arch = "arm";
os = "linux";
compression = "none";
load = <0>;
entry = <0>;
};
fdt@1 {
description = "tegra124-nyan-big.dtb";
data = /incbin/("./arch/arm/boot/dts/tegra124-nyan-big.dtb");
type = "flat_dt";
arch = "arm";
compression = "none";
hash@1 {
algo = "sha1";
};
};
};
configurations {
default = "conf@1";
conf@1 {
kernel = "kernel@1";
fdt = "fdt@1";
};
};
};
Use mkimage to create the Kernel image:
# Create the Kernel imagine in the uboot format
mkimage -D "-I dts -O dtb -p 1024" -f its_script.its /mnt/rootfs/boot/vmlinuz
Sign the Kernel
# Write Kernel flags
cat > /mnt/rootfs/boot/kernel.flags <<EOF
console=tty1 console=ttyS0,115200n8 console=ttyS1,115200n8 verbose debug printk.time=1 root=/dev/sdaX rootwait rw rootfstype=btrfs rootflags=subvol=system/factory/run lsm.module_locking=0
EOF
# Sign Kernel
vbutil_kernel --pack /mnt/rootfs/boot/vmlinuz.signed \
--keyblock /usr/share/vboot/devkeys/kernel.keyblock \
--version 1 \
--signprivate /usr/share/vboot/devkeys/kernel_data_key.vbprivk \
--config /mnt/rootfs/boot/kernel.flags \
--vmlinuz /mnt/rootfs/boot/vmlinuz \
--arch arm
# Write the ChromiumOS Kernel to the first partition
dd if=/mnt/rootfs/boot/vmlinuz.signed of=/dev/sdX1 bs=4M
# Mark Kernel partition as good and set priority
cgpt add -i 1 -S 1 -T 5 -P 1 /dev/sdX
# Unmount the partition
umount /mnt/rootfs
Baserock Setup
Attach the USB HDD or insert the SD to the Chromebook and press Ctrl-U to boot into the Kernel partition.
Once booted attach a USB Ethernet adapter and do:
# Set up systemd-network daemon
cat > /usr/lib/systemd/network/mynetwork.network <<EOF
[Network]
DHCP=v4
DNS=8.8.8.8
EOF
# Start network daemon
systemctl start systemd-networkd
# Set password
passwd root
# Find out the IP
ifconfig -a
# Increase /tmp size
mount -o remount,size=10G tmpfs /tmp/
# Create /src
mkdir /src/
From your main machine you can connect via SSH and mount /src:
# Copy SSH key
ssh-copy-id root@IPADDR
# Login from main machine
ssh root@IPADDR
# Create directory
mkdir ~/ssh-src
# Mount /src on your main machine
sshfs -o idmap=user -d root@IPADDR:/src ~/ssh-src
Init and build a Baserock system:
# Create /src/morph.conf
# ln -sv /src/morph.conf /etc/morph.conf
# Set Git identity
git config --global user.name "John Doe"
git config --global user.email johndoe@example.com
# Clone definitions
git clone git://git.baserock.org/baserock/baserock/definitions
cd definitions
# Build your first system
morph build systems/weston-system-armv7lhf-jetson.morph