mirror of
https://github.com/cloud-hypervisor/cloud-hypervisor.git
synced 2024-11-09 05:10:07 +00:00
92 lines
3.2 KiB
Markdown
92 lines
3.2 KiB
Markdown
# HOWTO VirtioFS rootfs
|
|
|
|
A quick guide for using virtiofs as a cloud-hypervisor guest's rootfs (i.e.
|
|
with no root block device). This document is a quick getting started guide.
|
|
There are many more steps to take to make this a production ready, secure
|
|
setup.
|
|
|
|
## Prerequisites
|
|
|
|
1. virtiofsd from the qemu project
|
|
* We are using the Qemu version for now
|
|
* There is a Rust version being worked on that may be a better option in the future
|
|
* Part of the qemu-system-common package on Ubuntu
|
|
* Part of the qemu-common package on Fedora
|
|
2. cloud-hypervisor - the newer the better, but I tested with 0.12
|
|
3. a rootfs - This howto uses an alpine rootfs available here:
|
|
* https://dl-cdn.alpinelinux.org/alpine/v3.13/releases/x86_64/alpine-minirootfs-3.13.2-x86_64.tar.gz
|
|
* Others should work
|
|
|
|
## To create the VM rootfs
|
|
|
|
```bash
|
|
mkdir rootfs/
|
|
cd rootfs
|
|
# this needs sudo to be able to set root permissions on fs components
|
|
sudo tar -xf /path/to/alpine-minirootfs-3.13.1-x86_64.tar.gz
|
|
# this will get created when the VM actually boots by the dhcp client
|
|
# but we need it in the chroot to download packages
|
|
sudo cp /etc/resolv.conf etc/
|
|
# the alpine mini rootfs is meant for docker containers, we need a few extra
|
|
# things for a working rootfs
|
|
sudo chroot $PWD apk add openrc busybox-initscripts
|
|
# we are using the paravirt console in cloud-hypervisor, so enable it in init
|
|
# append it after the other console since it doesn't work just appending it
|
|
sudo sed -i '/vt100/a \n# paravirt console\nhvc0::respawn:/sbin/getty -L hvc0 115200 vt100' etc/inittab
|
|
# set no password for root user... you obviously don't want to do this for
|
|
# any sort of production setup
|
|
sudo sed -i 's/root:!::0:::::/root:::0:::::/' etc/shadow
|
|
# set up init scripts
|
|
for i in acpid crond
|
|
sudo ln -sf /etc/init.d/$i etc/runlevels/default/$i
|
|
end
|
|
for i in bootmisc hostname hwclock loadkmap modules networking swap sysctl syslog urandom
|
|
sudo ln -sf /etc/init.d/$i etc/runlevels/boot/$i
|
|
end
|
|
|
|
for i in killprocs mount-ro savecache
|
|
sudo ln -sf /etc/init.d/$i etc/runlevels/shutdown/$i
|
|
end
|
|
|
|
for i in devfs dmesg hwdrivers mdev
|
|
sudo ln -sf /etc/init.d/$i etc/runlevels/sysinit/$i
|
|
end
|
|
# setup network config
|
|
echo 'auto lo
|
|
iface lo inet loopback
|
|
|
|
auto eth0
|
|
iface eth0 inet dhcp
|
|
' | sudo tee etc/network/interfaces
|
|
|
|
```
|
|
|
|
## To run the VM
|
|
|
|
```bash
|
|
# starting in the directory above rootfs
|
|
sudo virtiofsd --socket-path=$PWD/virtiofs-rootfs.sock --shared-dir=$PWD/rootfs --cache=never &
|
|
sudo cloud-hypervisor \
|
|
--cpus boot=1,max=1 \
|
|
--kernel vmlinux \
|
|
--fs tag=/dev/root,socket=$PWD/virtiofs-rootfs.sock \
|
|
--memory size=2G,shared=on \
|
|
--cmdline "console=hvc0 rootfstype=virtiofs root=/dev/root ro debug" \
|
|
--api-socket $PWD/ch.sock \
|
|
--rng \
|
|
--net ...
|
|
```
|
|
|
|
Note: an important part of the above is the `tag=/dev/root` and
|
|
`root=/dev/root` parts. For whatever reason, it would only work with that as
|
|
the tag.
|
|
|
|
Note: another important bit is that the memory is shared. This is required for
|
|
virtiofs
|
|
|
|
## Message from the author
|
|
|
|
If you find any issues or have suggestions, feel free to reach out to @iggy on
|
|
the cloud-hypervisor slack. Also if this works for you, I'd like to know as
|
|
well. It would also be nice to get steps for preparing other distribution root
|
|
filesystems. |