| 48 | | |
| 49 | | [=#debootstrap] |
| 50 | | == Root filesystem == |
| 51 | | This is to build the rootfs ONLY. To easily build an entire system image, including the boot firmware and Ubuntu, consider the [wiki:newport/bsp Newport BSP] page. |
| 52 | | |
| 53 | | A popular way to create an Ubuntu root filesystem is to use the {{{deboostrap}}} utility on a Debian or Ubuntu host. This tool provides a 2-stage install where the second stage is within a chroot environment using qemu. |
| 54 | | |
| 55 | | Gateworks uses a script to do this which you may find at http://github.com/Gateworks/ubuntu-rootfs |
| 56 | | |
| 57 | | Requirements: |
| 58 | | - Linux Ubuntu or Debian System with network connection and sudo permissions |
| 59 | | |
| 60 | | Important notes: |
| 61 | | * We set and use '''target''' and '''distro''' env variables in step 2 and use those env variables in the remaining steps to make this tutorial more version-agnostic. Please be aware of this and do not deviate from the steps unless or until you completely understand what you are doing. |
| 62 | | * These steps are not always exactly what we do in our script but give you an idea of how you would go about doing it yourself if you wanted to customize something |
| 63 | | |
| 64 | | Steps: |
| 65 | | 1. Install pre-requisites: |
| 66 | | {{{ |
| 67 | | #!bash |
| 68 | | sudo apt-get install qemu-user-static debootstrap binfmt-support |
| 69 | | }}} |
| 70 | | |
| 71 | | 2. Perform first stage install of minimal filesystem for {{{arm64}}} architecture: |
| 72 | | {{{#!bash |
| 73 | | distro=focal |
| 74 | | arch=arm64 |
| 75 | | target=${distro}-${arch} |
| 76 | | qemu_arch=aarch64 |
| 77 | | sudo debootstrap --arch=$arch --foreign $distro $target |
| 78 | | # copy qemu binary for the binfmt packages to find it and copy in resolv.conf from host |
| 79 | | sudo cp /usr/bin/qemu-${qemu_arch}-static $target/usr/bin |
| 80 | | }}} |
| 81 | | * See http://ports.ubuntu.com/ubuntu-ports/dists/ for a list of current Ubuntu releases: oe 20.04=focal (latest LTS) |
| 82 | | * this minimal rootfs is still missing some core packages and configuration before it can be booted. These steps are taken care of in a 2nd stage install within a chroot shell |
| 83 | | * the chroot shell below will provide network support (inherited from the host) |
| 84 | | |
| 85 | | 3. We now have a minimal Ubuntu rootfs - chroot to it and perform the 2nd stage install: |
| 86 | | {{{ |
| 87 | | #!bash |
| 88 | | sudo chroot $target |
| 89 | | # now we are in the chroot - setup env matching the distro above |
| 90 | | distro=focal |
| 91 | | export LANG=C |
| 92 | | # setup second stage |
| 93 | | /debootstrap/debootstrap --second-stage |
| 94 | | }}} |
| 95 | | * this is the most minimal rootfs we would recommend |
| 96 | | |
| 97 | | 4. (optional) add additional apt package repos: |
| 98 | | {{{ |
| 99 | | #!bash |
| 100 | | cat <<EOT > /etc/apt/sources.list |
| 101 | | deb http://ports.ubuntu.com/ubuntu-ports $distro main restricted universe multiverse |
| 102 | | deb http://ports.ubuntu.com/ubuntu-ports $distro-updates main restricted universe multiverse |
| 103 | | deb http://ports.ubuntu.com/ubuntu-ports $distro-security main restricted universe multiverse |
| 104 | | EOT |
| 105 | | }}} |
| 106 | | * you may want to customize the above list, depending on your needs. See [#packages below] for more detail on Ubuntu package feeds |
| 107 | | |
| 108 | | 5. (optional) update package database and setup locales (do not skip this step if you are needing to install any packages for the steps below or otherwise) |
| 109 | | {{{ |
| 110 | | #!bash |
| 111 | | apt-get update |
| 112 | | apt-get -f install # fixup missing package dependencies |
| 113 | | apt-get install locales dialog |
| 114 | | dpkg-reconfigure locales |
| 115 | | }}} |
| 116 | | |
| 117 | | 6. Set hostname: |
| 118 | | {{{ |
| 119 | | #!bash |
| 120 | | echo ${distro}-$(uname -m) > /etc/hostname |
| 121 | | }}} |
| 122 | | |
| 123 | | 7. set a root passwd so you can login |
| 124 | | {{{ |
| 125 | | #!bash |
| 126 | | passwd |
| 127 | | }}} |
| 128 | | - or consider adding a user via {{{adduser}}}: |
| 129 | | {{{ |
| 130 | | #!bash |
| 131 | | adduser myuser |
| 132 | | usermod -a -G tty myuser # add to tty group for tty access |
| 133 | | usermod -a -G dialout myuser # add to dialout group for UART access |
| 134 | | usermod -a -G sudo myuser # add to sudo group for root access |
| 135 | | }}} |
| 136 | | |
| 137 | | 8. (optional) configure networking: |
| 138 | | - wired ethernet with DHCP on eth0 |
| 139 | | {{{#!bash |
| 140 | | apt-get install net-tools ifupdown |
| 141 | | cat <<EOF >> /etc/network/interfaces |
| 142 | | allow-hotplug eth0 |
| 143 | | auto eth0 |
| 144 | | iface eth0 inet dhcp |
| 145 | | |
| 146 | | EOF |
| 147 | | }}} |
| 148 | | - or static IP: |
| 149 | | {{{#!bash |
| 150 | | apt-get install net-tools ifupdown |
| 151 | | cat <<EOF >> /etc/network/interfaces |
| 152 | | allow-hotplug eth0 |
| 153 | | auto eth0 |
| 154 | | iface eth0 inet static |
| 155 | | address 192.168.1.1 |
| 156 | | netmask 255.255.255.0 |
| 157 | | gateway 192.168.1.254 |
| 158 | | |
| 159 | | EOF |
| 160 | | }}} |
| 161 | | - or wireless (requires ~3MB of additional packages): |
| 162 | | {{{ |
| 163 | | #!bash |
| 164 | | apt-get install wpasupplicant iw |
| 165 | | cat << EOF >> /etc/network/interfaces |
| 166 | | # Wireless interface |
| 167 | | auto wlan0 |
| 168 | | iface wlan0 inet dhcp |
| 169 | | wireless_mode managed |
| 170 | | wireless_essid any |
| 171 | | wpa-driver nl80211 |
| 172 | | wpa-conf /etc/wpa_supplicant.conf |
| 173 | | |
| 174 | | EOF |
| 175 | | wpa_passphrase <myssid> <mypass> >> /etc/wpa_supplicant.conf |
| 176 | | }}} |
| 177 | | |
| 178 | | 9. (optional) install some useful packages |
| 179 | | {{{ |
| 180 | | #!bash |
| 181 | | apt-get install openssh-server # ssh server for remote access |
| 182 | | apt-get install can-utils i2c-tools usbutils pciutils # cmdline tools for various hardware support |
| 183 | | }}} |
| 184 | | * Note that by default root ssh access is disabled for security. See [wiki:/ubuntu#SSHServer This link] for info on enabling it |
| 185 | | |
| 186 | | 10. Exit the chroot shell and remove files we no longer need |
| 187 | | {{{ |
| 188 | | #!bash |
| 189 | | exit |
| 190 | | sudo rm $target/usr/bin/qemu-$qemu_arch-static |
| 191 | | }}} |
| 192 | | |
| 193 | | At this point you have a directory containing a root filesystem (without kernel) and likely want to install it onto removable storage or the on-board FLASH of a target board. Some intermediate formats that are useful to keep around would be a tarball, perhaps an ext4 filesystem image, or a compressed disk image suitable for flashing in the U-Boot bootloader. |
| 194 | | |
| 195 | | To create a tarball which is the most flexible storage format and can be used for a variety of future installation uses: |
| 196 | | {{{#!bash |
| 197 | | sudo tar --keep-directory-symlink -cvJf focal-newport.tar.xz -C rootfs/ . |
| 198 | | }}} |
| 199 | | * '--numeric-owner' is required to store user/group as a number instead of a name, your specific use case may require this switch. |
| 200 | | * the '-C rootfs/' is required to eliminate the rootfs directory prefix |
| 201 | | * the sudo is needed to be able to read the root owned files |
| 202 | | * '--keep-directory-symlink' will preserve symbolic links |
| 203 | | |
| 204 | | |
| 205 | | === Compressed Disk Image (for flashing onto a board) |
| 206 | | To create a 'Compressed Disk Image' using this tarball see [wiki:newport/boot#disk-images newport/boot#disk-images] and to install this onto a board's embedded FLASH see [wiki:newport#serial-ethernet here]. |
| 207 | | |
| 208 | | |
| 209 | | === ext4 filesystem === |
| 210 | | If desired you can create an ext4 filesystem from the directory or tarball. This requires you choose a size for the filesystem. This size can be increased at runtime using {{{resize2fs}}} as long as the partition table has room for it to grow. The advantage of using an as small as possible size is that the time necessary to flash it onto storage is reduced to a minimum (when flashing you have to write the entire ext4 fs but when formatting or resizing it only has to write periodic markers to FLASH). |
| 211 | | |
| 212 | | For a given size (see SIZEMB variable below) you can create a rootfs with: |
| 213 | | {{{#!bash |
| 214 | | SIZEMB=1536 # 1.5GB - expandable later with resize2fs |
| 215 | | OUT=rootfs.ext4 |
| 216 | | # create a file of specific size |
| 217 | | truncate -s ${SIZEMB}M ${OUT} |
| 218 | | # format it as an ext4 filesystem |
| 219 | | mkfs.ext4 -q -F -L rootfs ${OUT} |
| 220 | | # mount it to a temporary mount point |
| 221 | | tmp_mnt=$(mktemp -d -p/tmp) |
| 222 | | mount ${OUT} ${tmp_mnt} |
| 223 | | # copy files to it |
| 224 | | cp -rup rootfs/* ${tmp_mnt} |
| 225 | | # and/or extract files from a tarball |
| 226 | | tar -C ${tmp_mnt} -xf linux-newport.tar.xz |
| 227 | | # unmount temporary mount point |
| 228 | | umount ${tmp_mnt} |
| 229 | | sync |
| 230 | | # compress it |
| 231 | | gzip -k -f ${OUT} |
| 232 | | }}} |
| 233 | | |
| 234 | | Note that the pre-built Gateworks images create a minimal root filesystem as well as a partition table that assumes a specific size (matching the smallest eMMC device used on our boards). There is a script similar to the one above that runs on first-boot which expands the last partition to the extents of the device and grows the partition to fill it. See https://github.com/Gateworks/ubuntu-rootfs/blob/master/ubuntu-rootfs.sh and look for 'growpart' for details. |
| | 48 | == Root Filesystem |
| | 49 | see [wiki:ubuntu] |
