| (This document partly also applies to other Linuxes) |
| |
| Choosing an installer ISO |
| ------------------------- |
| |
| The last ISO installer version of Archlinux that supports 32-bit is [2017.02.01](https://www.archlinux.org/releng/releases/2017.02.01/). Later versions of the archisos don't work on the v86 emulator because the installer only supports x86_64, not x86 anymore. For existing Archlinux installations, updates and patches will be done until somewhere around 2018. |
| |
| In the future the community might come up with an alternative distribution based on Archlinux to maintain support for x86. At this point in time [archlinux32](https://mirror.archlinux32.org) seems to work. |
| |
| Basic installation using QEMU |
| ----------------------- |
| |
| Installing Archlinux like this will result in a raw disk image that can be booted by v86. |
| |
| ```sh |
| # Create a 10 gigabyte disk image. If you intend to pacstrap only 'base' then 1.5G should be fine also. |
| qemu-img create arch.img 10G |
| |
| # Follow the normal installation process (you can add accel=kvm if your system supports it to speed up the installation) |
| qemu-system-x86_64 -m 256 -drive file=arch.img,format=raw -cdrom archlinux-2017.02.01-dual.iso |
| ``` |
| |
| For keyboard support it is necessary to open /etc/mkinitcpio.conf and edit the following line: |
| |
| ```sh |
| MODULES="atkbd i8042" |
| ``` |
| |
| For the changes to take effect you need to regenerate the RAMdisk with `mkinitcpio -p linux` |
| |
| The resulting `arch.img` is a bootable disk image for v86. |
| |
| Scripting image creation for v86 |
| -------------------------------- |
| |
| Installing the ISO by hand takes a long time if you intend to recreate the image many times. There are various reasons why you might want to do this more than once. For example: because the emulator is slow you might want to compile any new software release in QEMU which is much faster and then use the resulting image in v86 instead of making the emulator compile the software. Another reason is that the build progress potentially takes long and if you want to do automated builds in parallel to find out what configurations do and don't work you can just throw more computing power at the problem in order to solve it. This example requires that you have `packer`, `qemu` and `kpartx` installed. |
| |
| ### Creating a packer template |
| |
| [Packer](https://www.packer.io/docs/builders/qemu.html) is a tool that lets you boot an ISO in any of multiple emulators (so QEMU in our case) and send pre-scripted keystrokes to bootstrap and SSH server. Once the SSH connection is established a script can be started for further provisioning. |
| |
| Create a template for automating the base installation |
| ```sh |
| mkdir -p packer |
| cat > packer/template.json << 'EOF' |
| { |
| "provisioners": [ |
| { |
| "type": "shell", |
| "override": { |
| "qemu": { |
| "scripts": ["scripts/provision.sh"] |
| } |
| } |
| } |
| ], |
| "builders": [ |
| { |
| "type": "qemu", |
| "boot_command": [ |
| "<enter><wait10>", |
| "dhcpcd<enter><wait10>", |
| "usermod --password $(echo toor | openssl passwd -1 -stdin) root<enter><wait10>", |
| "systemctl start sshd<enter>" |
| ], |
| "headless": true, |
| "boot_wait": "10s", |
| "disk_size": 1500, |
| "disk_interface": "ide", |
| "http_directory": "http", |
| "iso_url": "https://mirror.archlinux32.org/archisos/archlinux-2017.04.01-i686.iso", |
| "iso_checksum": "aa4718837c95e607233aecca43824c08c798b1a4", |
| "iso_checksum_type": "sha1", |
| "ssh_wait_timeout": "120s", |
| "ssh_pty": true, |
| "ssh_username": "root", |
| "ssh_password": "toor", |
| "ssh_port": 22, |
| "format": "raw", |
| "vm_name": "Archlinux-v86" |
| } |
| ] |
| } |
| EOF |
| ``` |
| |
| You can tweak the options a bit to match your situation. For debugging you can set `headless` to `false`. That will show you the vnc instead of running the `boot_command` in the background. For a `base` pacstrap using a 1.5G disk should be sufficient. The `raw` disk format is important. v86 does not read qcow2 images, only raw disk images. If your system does not support kvm (the default accelerator), you can add `"accelerator": "none"` to the settings. Other accelerator options can be found [here](https://www.packer.io/docs/builders/qemu.html#accelerator). |
| |
| After gaining SSH connectivity to the VM, packer will run the `scripts/provisioning.sh` script in the guest. |
| |
| ### Creating the Archlinux installation script |
| |
| Create a script for your Archlinux installation. This runs in the ISO booted Archlinux environment, so you need to partition, pacstrap and install a bootloader. |
| ```sh |
| mkdir -p packer/scripts |
| ### Write your own or copy paste the example below |
| vim packer/scripts/provision.sh |
| ``` |
| |
| An example script to install Archlinux with the root mounted using the 9p network filesystem: |
| ```sh |
| #!/bin/bash |
| echo "Creating a GPT partition on /dev/sda1" |
| echo -e "g\nn\n\n\n\nw" | fdisk /dev/sda |
| |
| # In case you might want to create a DOS partition instead. It doesn't really matter. |
| #echo "Creating a DOS partition on /dev/sda1" |
| #echo -e "o\nn\np\n1\n\n\nw" | fdisk /dev/sda |
| |
| echo "Formatting /dev/sda1 to ext4" |
| mkfs -t ext4 /dev/sda1 |
| |
| echo "Mounting new filesystem" |
| mount -t ext4 /dev/sda1 /mnt |
| |
| echo "Create pacman package cache dir" |
| mkdir -p /mnt/var/cache/pacman/pkg |
| |
| # We don't want the pacman cache to fill up the image. After reboot whatever tarballs pacman has cached are gone. |
| echo "Mount the package cache dir in memory so it doesn't fill up the image" |
| mount -t tmpfs none /mnt/var/cache/pacman/pkg |
| |
| # Install the Archlinux base system |
| echo "Performing pacstrap" |
| pacstrap -i /mnt base --noconfirm |
| |
| echo "Writing fstab" |
| genfstab -p /mnt >> /mnt/etc/fstab |
| |
| # When the Linux boots we want it to automatically log in on tty1 as root |
| echo "Ensuring root autologin on tty1" |
| mkdir -p /mnt/etc/systemd/system/getty@tty1.service.d |
| cat << 'EOF' > /mnt/etc/systemd/system/getty@tty1.service.d/override.conf |
| [Service] |
| ExecStart= |
| ExecStart=-/usr/bin/agetty --autologin root --noclear %I $TERM |
| EOF |
| |
| # This is the tricky part. The current root will be mounted on /dev/sda1 but after we reboot |
| # it will try to mount root during boot using the 9p network filesystem. This means the emulator |
| # will request all files over the network using XMLHttpRequests from the server. This is great |
| # because then you only need to provide the client with a saved state (the memory) and the |
| # session will start instantly and load needed files on the fly. This is fast and it saves bandwidth. |
| echo "Ensuring root is remounted using 9p after reboot" |
| mkdir -p /mnt/etc/initcpio/hooks |
| cat << 'EOF' > /mnt/etc/initcpio/hooks/9p_root |
| run_hook() { |
| mount_handler="mount_9p_root" |
| } |
| |
| mount_9p_root() { |
| msg ":: mounting '$root' on real root (9p)" |
| # Note the host9p. We won't mount /dev/sda1 on root anymore, |
| # instead we mount the network filesystem and the emulator will |
| # retrieve the files on the fly. |
| if ! mount -t 9p host9p "$1"; then |
| echo "You are now being dropped into an emergency shell." |
| launch_interactive_shell |
| msg "Trying to continue (this will most likely fail) ..." |
| fi |
| } |
| EOF |
| |
| echo "Adding initcpio build hook for 9p root remount" |
| mkdir -p /mnt/etc/initcpio/install |
| cat << 'EOF' > /mnt/etc/initcpio/install/9p_root |
| #!/bin/bash |
| build() { |
| add_runscript |
| } |
| EOF |
| |
| # We need to load some modules into the kernel for it to play nice with the emulator |
| # The atkbd and i8042 modules are for keyboard input in the browser. If you do not |
| # want to use the network filesystem you only need these. The 9p, 9pnet and 9pnet_virtio |
| # modules are needed for being able to mount 9p network filesystems using the emulator. |
| echo "Configure mkinitcpio for 9p" |
| sed -i 's/MODULES=""/MODULES="atkbd i8042 virtio_pci 9p 9pnet 9pnet_virtio"/g' /mnt/etc/mkinitcpio.conf |
| |
| # Because we want to mount the root filesystem over the network during boot, we need to |
| # hook into initcpio. If you do not want to mount the root filesystem during boot but |
| # only want to mount a 9p filesystem later, you can leave this out. Once the system |
| # has been booted you should be able to mount 9p filesystems with mount -t 9p host9p /blabla |
| # without this hook. |
| sed -i 's/fsck"/fsck 9p_root"/g' /mnt/etc/mkinitcpio.conf |
| |
| echo "Writing the installation script" |
| cat << 'EOF' > /mnt/bootstrap.sh |
| #!/usr/bin/bash |
| echo "Re-generate initial ramdisk environment" |
| mkinitcpio -p linux |
| |
| echo "Installing the grub package" |
| pacman -S os-prober grub --noconfirm |
| |
| echo "Setting grub timeout to 0 seconds" |
| sed -i 's/GRUB_TIMEOUT=5/GRUB_TIMEOUT=0/g' /etc/default/grub |
| |
| echo "Installing bootloader" |
| grub-install --target=i386-pc --recheck /dev/sda --force |
| |
| echo "Writing grub config" |
| grub-mkconfig -o /boot/grub/grub.cfg |
| sync |
| EOF |
| |
| echo "Chrooting and bootstrapping the installation" |
| arch-chroot /mnt bash bootstrap.sh |
| |
| umount -R /mnt |
| ``` |
| |
| With the packer template and the script you have enough to create an image that can be booted by v86. But because this example script installs an Archlinux that wants to mount root over the network with 9p, we need to host that filesystem first. If you do not want to use 9p, you can just run `(cd packer && packer build -force template.json)` to build the image. |
| |
| ### Creating the 9p filesystem |
| |
| Now that we have an image that contains a filesystem, we can convert that filesystem into something we can host on the webserver together with the v86 library. |
| |
| To do so, we need to mount the image once and create a json mapping of the filesystem. This can be done with the [fs2json](https://github.com/copy/fs2json) python script. |
| |
| Get the script: |
| ```sh |
| wget https://raw.githubusercontent.com/copy/fs2json/master/fs2json.py |
| ``` |
| |
| The following script shows how to map the filesystem in an automated fashion. |
| |
| Create a script to builds the image and then creates v86 compatible artifacts: |
| ```sh |
| vim build.sh |
| ``` |
| |
| Example script: |
| |
| ```sh |
| #!/bin/sh |
| |
| # build the boxfile from the iso |
| (cd packer && packer build -force template.json) |
| |
| # test if there is a boxfile where we expected it |
| if [ ! -f packer/output-qemu/Archlinux-v86 ]; then |
| echo "Looks like something went wrong building the image, maybe try again?" |
| exit 1 |
| fi; |
| |
| # clean up any previous loops and mounts |
| echo "Making sure mountpoint is empty" |
| sudo umount diskmount -f || /bin/true |
| sudo kpartx -d /dev/loop0 || /bin/true |
| sudo losetup -d /dev/loop0 || /bin/true |
| |
| # mount the generated raw image, we do that so we can create |
| # a json mapping of it and copy it to host on the webserver |
| mkdir -p diskmount |
| echo "Mounting the created image so we can convert it to a p9 image" |
| sudo losetup /dev/loop0 packer/output-qemu/Archlinux-v86 |
| sudo kpartx -a /dev/loop0 |
| sudo mount /dev/mapper/loop0p1 diskmount |
| |
| # make images dir |
| mkdir -p output/images |
| |
| # map the filesystem to json with fs2json |
| sudo python fs2json.py --exclude /boot/ --out output/images/fs.json diskmount |
| |
| # copy the filesystem and chown to nonroot user |
| echo "Copying the filesystem to output/arch" |
| mkdir output/arch -p |
| sudo rsync -q -av diskmount/ output/arch |
| sudo chown -R $(whoami):$(whoami) output/arch |
| |
| # clean up mount |
| echo "Cleaning up mounts" |
| sudo umount diskmount -f |
| sudo kpartx -d /dev/loop0 |
| sudo losetup -d /dev/loop0 |
| |
| # Move the image to the images dir |
| mv packer/output-qemu/Archlinux-v86 output/images/arch.img |
| ``` |
| |
| An example repository with these scripts can be found [here](https://github.com/vdloo/archlinux-v86-builder) |
| |
| ### Using the created artifacts in v86 |
| |
| Now that we have everything we need to host a server that serves an Archlinux environment over the network. |
| |
| Create a checkout of v86 and run `make build/libv86.js`. Then edit `examples/arch.html` and replace the `hda` and `filesystem` section with something like this: |
| ```sh |
| hda: { |
| url: "http://localhost:8000/images/arch.img", |
| async: true, # For this option we need to run a webserver that supports the Range header |
| size: 1.5 * 1024 * 1024 * 1024, # This needs to be the size of the raw disk. |
| # See the `disk_size` item in the packer template. |
| }, |
| filesystem: { |
| baseurl: "http://localhost:8000/arch/", |
| basefs: "http://localhost:8000/images/fs.json", |
| }, |
| ``` |
| |
| Then copy the created image, filesystem and json file to the v86 directory: |
| ```sh |
| cp -f /your/packer/dir/output/images/arch.img /your/v86/dir/images/arch.img |
| cp -f /your/packer/dir/output/images/fs.json /your/v86/dir/images/fs.json |
| cp -r /your/pacher/dir/output/arch /your/v86/dir/ |
| ``` |
| |
| Next, we need a webserver that supports the Range header. For example [this extension of the SimpleHTTPServer](https://github.com/smgoller/rangehttpserver). |
| |
| ```sh |
| cd /your/v86/dir |
| wget https://raw.githubusercontent.com/smgoller/rangehttpserver/master/RangeHTTPServer.py |
| python2 RangeHTTPServer.py |
| ``` |
| |
| Now that the webserver is running, point your browser to `http://localhost:8000/examples/arch.html`. Wait for the Linux to boot. When the system is up, click 'Save state to file'. Your browser will download a `v86state.bin` file. Copy that file to `/your/v86/dir/images`. You can then edit `examples/arch.html` again and add a 'state' key to the `V86Starter` array. |
| |
| ```sh |
| state: { |
| "url": ""http://localhost:8000/images/v86state.bin, |
| "size": the_size_of_your_state, # You can get this by running `stat v86state.bin` |
| }, |
| ``` |
| |
| If you refresh `http://localhost:8000/examples/arch.html` you will see that the state is restored instantly and all required files are loaded over the network on the fly. |