ezkernel
It just builds a kernel.
$ make build
How to get a microvm up and running with this project.
$ make build
$ mkdir -p initramfs-src/bin
$ curl -Lo initramfs-src/bin/busybox https://www.busybox.net/downloads/binaries/1.31.0-defconfig-multiarch-musl/busybox-x86_64
$ echo '#!/bin/busybox sh' > initramfs-src/init
$ echo '/bin/busybox sh' >> initramfs-src/init
$ chmod +x initramfs-src/bin/busybox initramfs-src/init
$ cd initramfs-src && find . | cpio -o -H newc | gzip > ../initramfs && cd -
$ qemu-system-x86_64 \
-M microvm,x-option-roms=off,isa-serial=off \
-no-acpi -no-user-config -no-reboot \
-smp 2 -m 2048 \
-kernel bzImage -initrd initramfs \
-device virtio-serial-device -chardev stdio,id=virtiocon0 -device virtconsole,chardev=virtiocon0 \
-netdev "user,id=net0,${PORTS}" \
-device virtio-net-device,netdev=net0 \
-append "console=hvc0 ip=dhcp nameserver=8.8.8.8 nameserver=8.8.4.4 init=/init" \
-display none
At this point, you should have a root console open in your terminal. Installing busybox is done like so.
# mkdir -p /bin /sbin /usr/sbin /usr/bin
# /bin/busybox --install -s
Mounts are done like this.
# mkdir -p /proc /dev /sys /tmp /run
# mount -t proc proc /proc
# mount -t proc proc /dev
# mount -t sysfs sysfs /sys
# mount -t tmpfs tmpfs /tmp
# mount -t tmpfs tmpfs /run
# mkdir -p /dev/pts /dev/mqueue
# mount -t devpts devpts /dev/pts
# mount -t mqueue mqueue /dev/mqueue
# mount -t cgroup cgroup /sys/fs/cgroup
Anything you can setup at this point manually can be don with the init file that
was made in initramfs-src/init. Look into things like switch_root, perhaps
check out alpine's init script.
It uses busybox as well.
- glhf
Why?
Just needed a kernel that works with qemu for microvms that supported mounting a 9p file system at root.
Todo
- Build the latest kernel. Dockerfiles are hard coded to build 5.15.
- Add a file with kernel version at /version.txt