added virtio post

4 files changed, 258 insertions, 0 deletions

diff --git a/content/2021-12-02-toying-with-virtio/Dockerfile b/content/2021-12-02-toying-with-virtio/Dockerfile
new file mode 100644
index 0000000..f892fef
--- /dev/null
+++ b/content/2021-12-02-toying-with-virtio/Dockerfile
@@ -0,0 +1,44 @@
+FROM ubuntu:20.04
+MAINTAINER Johannes Stoelp <johannes.stoelp@gmail.edu>
+
+ARG UID
+
+RUN apt update                     \
+ && DEBIAN_FRONTEND=noninteractive \
+    apt install                    \
+      --yes                        \
+      --no-install-recommends      \
+      # Download & unpack.
+      wget                         \
+      ca-certificates              \
+      xz-utils                     \
+      # Build tools & deps (kernel).
+      make                         \
+      bc                           \
+      gcc g++                      \
+      flex bison                   \
+      libelf-dev                   \
+      libncurses-dev               \
+      # Build tools & deps (initrd).
+      cpio                         \
+      # Run & debug.
+      qemu-system-x86              \
+      # Convenience.
+      sudo                         \
+      telnet                       \
+      ripgrep                      \
+      fd-find                      \
+      neovim                       \
+ && rm -rf /var/lib/apt/lists/*    \
+ && apt-get clean
+
+# Allow 'user' to use sudo without password.
+# Convenience in case we want to install some packages in the container later.
+RUN echo "user ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers.d/user
+
+# Create user with the UID passed during docker build.
+RUN useradd --create-home --home-dir /home/user --uid $UID --shell /bin/bash user
+# Start container with user.
+USER user
+# Change default working dir.
+WORKDIR /develop
diff --git a/content/2021-12-02-toying-with-virtio/Makefile b/content/2021-12-02-toying-with-virtio/Makefile
new file mode 100644
index 0000000..4009862
--- /dev/null
+++ b/content/2021-12-02-toying-with-virtio/Makefile
@@ -0,0 +1,57 @@
+VER := 5.15.6
+
+all: kernel init
+
+help:
+	@echo "Build targets:"
+	@echo "* init       - Build busybox based initramfs."
+	@echo "* kernel     - Build minimal linux kernel."
+	@echo "  clean      - Cleanup downloads & builds."
+	@echo ""
+	@echo "Run targets:"
+	@echo "  run        - Boot into the initramfs (qemu)."
+	@echo "  vcon       - Attach to guest virtio console."
+	@echo "               This needs an already running guest VM and must be"
+	@echo "               executed in the same domain as the 'run' target"
+	@echo "               (docker or host)."
+	@echo "               Login as 'root' user, no passwd required."
+	@echo ""
+	@echo "Docker targets:"
+	@echo "  docker     - Build and start the docker container."
+	@echo "  attach     - Start an additional bash in the container."
+	@echo "               This needs an already running container."
+
+kernel:
+	./build_kernel.sh
+
+init:
+	./build_initramfs.sh
+
+run:
+	qemu-system-x86_64                                            \
+	  -nographic                                                  \
+	  -cpu host                                                   \
+	  -enable-kvm                                                 \
+	  -kernel ./linux-$(VER)/arch/x86/boot/bzImage                \
+	  -append "earlyprintk=ttyS0 console=ttyS0 root=/dev/ram0 ro" \
+	  -initrd ./initramfs.cpio.gz                                 \
+	  -device virtio-serial-pci                                   \
+	  -device virtconsole,chardev=vcon,name=console.0             \
+	  -chardev socket,id=vcon,ipv4=on,host=localhost,port=2222,server,telnet=on,wait=off \
+	  -drive format=raw,if=virtio,file=rootfs.ext2 \
+	  -nic user,model=virtio-net-pci
+
+vcon:
+	telnet -4 localhost 2222
+
+clean:
+	$(RM) initramfs.cpio.gz
+	$(RM) -r busybox-*
+	$(RM) -r linux-$(VER)*
+
+docker:
+	DOCKER_BUILDKIT=1 docker build --build-arg UID=$(shell id -u) -t virtio-dev .
+	docker run --name virtio -it --rm -v $(PWD):/develop --device /dev/kvm virtio-dev
+
+attach:
+	docker exec -it virtio bash
diff --git a/content/2021-12-02-toying-with-virtio/build_initramfs.sh b/content/2021-12-02-toying-with-virtio/build_initramfs.sh
new file mode 100755
index 0000000..c30fa5e
--- /dev/null
+++ b/content/2021-12-02-toying-with-virtio/build_initramfs.sh
@@ -0,0 +1,90 @@
+#!/bin/bash
+
+set -e
+
+BUSYBOX=busybox-1.34.1
+INITRAMFS=$PWD/initramfs.cpio.gz
+
+## Build busybox (static).
+
+test -f $BUSYBOX.tar.bz2 || wget -nc https://busybox.net/downloads/$BUSYBOX.tar.bz2
+test -d $BUSYBOX || tar xf $BUSYBOX.tar.bz2
+
+cd $BUSYBOX
+make defconfig
+sed -i 's/[# ]*CONFIG_STATIC[ =].*/CONFIG_STATIC=y/' .config
+make -j$(nproc) busybox
+make install
+
+## Create initramfs.
+
+cd _install
+
+# 1. Create initramfs folder structure.
+
+mkdir -p bin sbin etc/init.d proc sys usr/bin usr/sbin dev mnt
+
+# 2. Prepare init.
+
+# By default, initramfs executes /init.
+# Optionally change with rdinit= kernel parameter.
+ln -sfn sbin/init init
+
+cat <<EOF > etc/inittab
+# Initialization after boot.
+::sysinit:/etc/init.d/rcS
+
+# Shell on console after user presses key.
+::askfirst:/bin/cttyhack /bin/sh -l
+
+# Spawn getty on first virtio console.
+::respawn:/sbin/getty hvc0 9600 vt100
+EOF
+
+cat <<EOF > etc/init.d/rcS
+#!/bin/sh
+
+# Mount devtmpfs, which automatically populates /dev with devices nodes.
+# So no mknod for our experiments :}
+mount -t devtmpfs none /dev
+
+# Mount procfs and sysfs.
+mount -t proc none /proc
+mount -t sysfs none /sys
+
+# Set hostname.
+hostname virtio-box
+EOF
+chmod +x etc/init.d/rcS
+
+cat <<EOF > etc/profile
+export PS1="\[\e[31m\e[1m\]\u@\h\[\e[0m\] \w # "
+EOF
+
+# 3. Create minimal passwd db with 'root' user and password '1234'.
+#    Mainly used for login on virtual console in this experiments.
+echo "root:x:0:0:root:/:/bin/sh" > etc/passwd
+echo "root:$(openssl passwd -crypt 1234):0::::::" > etc/shadow
+
+# 4. Create minimal setup for basic networking.
+
+# Virtul DNS from qemu user network.
+echo "nameserver 10.0.2.3" > etc/resolv.conf
+
+# Assign static IP address, bring-up interface and define default route.
+cat <<EOF >> etc/init.d/rcS
+# Assign static IP address to eth0 interface.
+ip addr add 10.0.2.15/24 dev eth0
+
+# Bring up eth0 interface.
+ip link set dev eth0 up
+
+# Add default route via the host (qemu user networking exposes host at this
+# address by default).
+ip route add default via 10.0.2.2
+EOF
+
+# 5. Created cpio compressed initramfs.
+find . -print0                      \
+    | cpio --null -ov --format=newc \
+    | gzip -9 > $INITRAMFS
diff --git a/content/2021-12-02-toying-with-virtio/build_kernel.sh b/content/2021-12-02-toying-with-virtio/build_kernel.sh
new file mode 100755
index 0000000..b219b57
--- /dev/null
+++ b/content/2021-12-02-toying-with-virtio/build_kernel.sh
@@ -0,0 +1,67 @@
+#!/bin/bash
+
+set -e
+
+LINUX=linux-5.15.6
+
+test -f $LINUX.tar.xz || wget -nc https://cdn.kernel.org/pub/linux/kernel/v5.x/$LINUX.tar.xz
+test -d $LINUX || tar xf $LINUX.tar.xz
+
+cd $LINUX
+
+cat <<EOF > kernel_fragment.config
+# 64bit kernel.
+CONFIG_64BIT=y
+# Enable support for cpio compressed initramfs (gzip).
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_RD_GZIP=y
+# Support for ELF and #! binary format.
+CONFIG_BINFMT_ELF=y
+CONFIG_BINFMT_SCRIPT=y
+# Enable devtmpfs (can automatically populate /dev).
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+# Enable tty & console.
+CONFIG_TTY=y
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+# Enable proc & sys pseudo fs.
+CONFIG_PROC_FS=y
+CONFIG_SYSFS=y
+
+# Enable support for virtio pci.
+CONFIG_PCI=y
+CONFIG_VIRTIO_MENU=y
+CONFIG_VIRTIO_PCI=y
+
+# Enable virtio console driver.
+CONFIG_VIRTIO_CONSOLE=y
+
+# Enable support for block devices.
+CONFIG_BLK_DEV=y
+
+# Enable virtio blk driver.
+CONFIG_VIRTIO_BLK=y
+
+# Enable support for ext2 filesystems.
+CONFIG_EXT2_FS=y
+
+# Enable general networking support.
+CONFIG_NET=y
+
+# Enable support for TCP/IP.
+CONFIG_INET=y
+
+# Enable support for network devices.
+CONFIG_NETDEVICES=y
+
+# Enable networking core drivers.
+CONFIG_NET_CORE=y
+
+# Enable virtio net driver.
+CONFIG_VIRTIO_NET=y
+EOF
+
+make tinyconfig
+./scripts/kconfig/merge_config.sh -n ./kernel_fragment.config
+make -j$(nproc)