virt/qemu.nix · Nix · Filnix wiki

virt/qemu.nix

λpkgs, ports, filcc, world-pkgs

let

9common=

import./common.nix inherit pkgs ports filcc;

10inherit common

ghostty-terminfo dank-bashrc lighttpd-demo

Minimal headless QEMU without GUI dependencies

13qemu-headless=

pkgs.qemu_kvm.override

15hostCpuOnly=

true

Only build for host CPU architecture

16gtkSupport=

false

17sdlSupport=

false

18spiceSupport=

false

19ncursesSupport=

false

20smartcardSupport=

false

21usbredirSupport=

false

22vncSupport=

false

23openGLSupport=

false

24virglSupport=

false

25jackSupport=

false

26pulseSupport=

false

27pipewireSupport=

false

28alsaSupport=

false

29tpmSupport=

false

30smbdSupport=

false

31libiscsiSupport=

false

32glusterfsSupport=

false

33cephSupport=

false

used by imageBuilder

37core=

import./core.nix inherit pkgs ports world-pkgs dank-bashrc ghostty-terminfo lighttpd-demo;

50consoleDevice=

"/dev/ttyS0"

51mountFilesystems=

true

QEMU needs to mount everything

54inherit core

env mkRootfsScript

56kernel=

pkgs.linuxPackages_latest.kernel.override

57ignoreConfigErrors=

true

58autoModules=

false

60structuredExtraConfig=

with pkgs.lib.kernel

61VIRTIO=

yes

62VIRTIO_MENU=

yes

63VIRTIO_PCI=

yes

64VIRTIO_PCI_LIB=

yes

65VIRTIO_BLK=

yes

66MODVERSIONS=

pkgs.lib.mkForceno

Script that builds the rootfs and creates a disk image

71imageBuilder=

pkgs.writeShellScript"build-filc-qemu-image"

set -euo pipefail

output="''${1:-filc-rootfs.img}"

echo "Building Fil-C QEMU disk image: $output"

# Create temporary directory for rootfs

workdir=$(mktemp -d)

trap 'chmod -R +w "$workdir" 2>/dev/null || true; rm -rf "$workdir"' EXIT

rootfs="$workdir/rootfs"

mkdir -p "$rootfs"

# Build rootfs using shared script

echo "Assembling rootfs..."

${mkRootfsScript"$rootfs"}

# Calculate actual size needed (with 20% overhead)

actual_size=$(${pkgs.coreutils}/bin/du -sb "$rootfs" | ${pkgs.coreutils}/bin/cut -f1)

size_with_overhead=$((actual_size * 120 / 100))

echo "Rootfs size: $actual_size bytes (allocating $size_with_overhead bytes with overhead)"

# Create raw disk image

echo "Creating raw ext4 disk image..."

${pkgs.coreutils}/bin/truncate -s "$size_with_overhead" "$output"

# Format as ext4

${pkgs.e2fsprogs}/bin/mkfs.ext4 -q -L filc-root "$output"

# Mount and copy rootfs

echo "Copying rootfs to disk..."

mnt="$workdir/mnt"

mkdir -p "$mnt"

sudo ${pkgs.util-linux}/bin/mount -o loop "$output" "$mnt"

trap 'sudo ${pkgs.util-linux}/bin/umount "$mnt" 2>/dev/null || true; chmod -R +w "$workdir" 2>/dev/null || true; rm -rf "$workdir"' EXIT

sudo ${pkgs.rsync}/bin/rsync -a "$rootfs/" "$mnt/"

sudo ${pkgs.util-linux}/bin/umount "$mnt"

echo "Disk image created: $output"

${pkgs.coreutils}/bin/ls -lh "$output"

echo

echo "To compress for distribution:"

echo " ${qemu-headless}/bin/qemu-img convert -f raw -O qcow2 -c $output ''${output%.img}.qcow2"

uses mkRootfsScript qemu-headless

pkgs.buildEnv

120name=

"filc-qemu"

121paths=

pkgs.writeShellScriptBin"build-filc-qemu-image"

exec ${imageBuilder} "$@"

pkgs.writeShellScriptBin"run-filc-qemu"

set -euo pipefail

disk="''${1:-/tmp/filc.img}"

${imageBuilder} "$disk"

# Auto-detect format from extension

format="raw"

case "$disk" in

*.qcow2) format="qcow2" ;;

*.img|*.raw) format="raw" ;;

esac

qemu=${qemu-headless}/bin/qemu-system-x86_64

kernel=${kernel}/bzImage

accelFlags="-cpu max"

if [ -e /dev/kvm ] && [ -r /dev/kvm ] && [ -w /dev/kvm ]; then

accelFlags="-enable-kvm -cpu host"

else

echo "warning: /dev/kvm unavailable, falling back to TCG (-cpu max)" >&2

echo " Fil-C runtime may require modern CPU features; enable KVM if possible." >&2

echo "Starting Fil-C QEMU (disk: $disk, format: $format)..."

exec "$qemu" \

-m 512 \

-kernel "$kernel" \

-drive file="$disk",if=virtio,format="$format" \

-netdev user,id=net0,hostfwd=tcp:127.0.0.1:2222-:22 \

-device virtio-net-pci,netdev=net0 \

-append "console=ttyS0 root=/dev/vda rootwait init=/bin/runit-init panic=-1 oops=panic earlyprintk=serial,ttyS0,115200" \

-nographic \

-no-reboot \

$accelFlags

162pathsToLink=

"/bin"