{ config, lib, pkgs, ... }: with lib; with import ../tests/lib/qemu-flags.nix { inherit pkgs; }; let qemu = config.system.build.qemu; cfg = config.virtualisation; consoles = lib.concatMapStringsSep " " (c: "console=${c}") cfg.qemu.consoles; driveOpts = { ... }: { options = { file = mkOption { type = types.str; description = "The file image used for this drive."; }; driveExtraOpts = mkOption { type = types.attrsOf types.str; default = { }; description = "Extra options passed to drive flag."; }; deviceExtraOpts = mkOption { type = types.attrsOf types.str; default = { }; description = "Extra options passed to device flag."; }; name = mkOption { type = types.nullOr types.str; default = null; description = "A name for the drive. Must be unique in the drives list. Not passed to qemu."; }; }; }; driveCmdline = idx: { file, driveExtraOpts, deviceExtraOpts, ... }: let drvId = "drive${toString idx}"; mkKeyValue = generators.mkKeyValueDefault { } "="; mkOpts = opts: concatStringsSep "," (mapAttrsToList mkKeyValue opts); driveOpts = mkOpts (driveExtraOpts // { index = idx; id = drvId; "if" = "none"; inherit file; }); deviceOpts = mkOpts (deviceExtraOpts // { drive = drvId; }); device = if cfg.qemu.diskInterface == "scsi" then "-device lsi53c895a -device scsi-hd,${deviceOpts}" else "-device virtio-blk-pci,${deviceOpts}"; in "-drive ${driveOpts} ${device}"; drivesCmdLine = drives: concatStringsSep " " (imap1 driveCmdline drives); # Creates a device name from a 1-based a numerical index, e.g. # * `driveDeviceName 1` -> `/dev/vda` # * `driveDeviceName 2` -> `/dev/vdb` driveDeviceName = idx: let letter = elemAt lowerChars (idx - 1); in if cfg.qemu.diskInterface == "scsi" then "/dev/sd${letter}" else "/dev/vd${letter}"; lookupDriveDeviceName = driveName: driveList: (findSingle (drive: drive.name == driveName) (throw "Drive ${driveName} not found") (throw "Multiple drives named ${driveName}") driveList).device; addDeviceNames = imap1 (idx: drive: drive // { device = driveDeviceName idx; }); efiPrefix = if (pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64) then "${pkgs.buildPackages.OVMF.fd}/FV/OVMF" else if pkgs.stdenv.isAarch64 then "${pkgs.buildPackages.OVMF.fd}/FV/AAVMF" else throw "No EFI firmware available for platform"; efiFirmware = "${efiPrefix}_CODE.fd"; efiVarsDefault = "${efiPrefix}_VARS.fd"; # Shell script to start the VM. startVM = '' #! ${pkgs.buildPackages.runtimeShell} NIX_DISK_IMAGE=$(readlink -f ''${NIX_DISK_IMAGE:-${config.virtualisation.diskImage}}) if ! test -e "$NIX_DISK_IMAGE"; then ${qemu}/bin/qemu-img create -f qcow2 "$NIX_DISK_IMAGE" \ ${toString config.virtualisation.diskSize}M || exit 1 fi # Create a directory for storing temporary data of the running VM. if [ -z "$TMPDIR" -o -z "$USE_TMPDIR" ]; then TMPDIR=$(mktemp -d nix-vm.XXXXXXXXXX --tmpdir) fi # Create a directory for exchanging data with the VM. mkdir -p $TMPDIR/xchg ${if cfg.useBootLoader then '' # Create a writable copy/snapshot of the boot disk. # A writable boot disk can be booted from automatically. ${qemu}/bin/qemu-img create -f qcow2 -b ${bootDisk}/disk.img $TMPDIR/disk.img || exit 1 NIX_EFI_VARS=$(readlink -f ''${NIX_EFI_VARS:-${cfg.efiVars}}) ${if cfg.useEFIBoot then '' # VM needs writable EFI vars if ! test -e "$NIX_EFI_VARS"; then cp ${bootDisk}/efi-vars.fd "$NIX_EFI_VARS" || exit 1 chmod 0644 "$NIX_EFI_VARS" || exit 1 fi '' else ""} '' else ""} cd $TMPDIR idx=0 ${flip concatMapStrings cfg.emptyDiskImages (size: '' if ! test -e "empty$idx.qcow2"; then ${qemu}/bin/qemu-img create -f qcow2 "empty$idx.qcow2" "${ toString size }M" fi idx=$((idx + 1)) '')} # Start QEMU. exec ${qemuBinary qemu} \ -name ${config.system.name} \ -m ${toString config.virtualisation.memorySize} \ -smp ${toString config.virtualisation.cores} \ -device virtio-rng-pci \ ${concatStringsSep " " config.virtualisation.qemu.networkingOptions} \ -virtfs local,path=/nix/store,security_model=none,mount_tag=store \ -virtfs local,path=$TMPDIR/xchg,security_model=none,mount_tag=xchg \ -virtfs local,path=''${SHARED_DIR:-$TMPDIR/xchg},security_model=none,mount_tag=shared \ ${drivesCmdLine config.virtualisation.qemu.drives} \ ${toString config.virtualisation.qemu.options} \ $QEMU_OPTS \ "$@" ''; regInfo = pkgs.closureInfo { rootPaths = config.virtualisation.pathsInNixDB; }; # Generate a hard disk image containing a /boot partition and GRUB # in the MBR. Used when the `useBootLoader' option is set. # Uses `runInLinuxVM` to create the image in a throwaway VM. # See note [Disk layout with `useBootLoader`]. # FIXME: use nixos/lib/make-disk-image.nix. bootDisk = pkgs.vmTools.runInLinuxVM (pkgs.runCommand "nixos-boot-disk" { preVM = '' mkdir $out diskImage=$out/disk.img ${qemu}/bin/qemu-img create -f qcow2 $diskImage "60M" ${if cfg.useEFIBoot then '' efiVars=$out/efi-vars.fd cp ${efiVarsDefault} $efiVars chmod 0644 $efiVars '' else ""} ''; buildInputs = [ pkgs.utillinux ]; QEMU_OPTS = "-nographic -serial stdio -monitor none" + lib.optionalString cfg.useEFIBoot (" -drive if=pflash,format=raw,unit=0,readonly=on,file=${efiFirmware}" + " -drive if=pflash,format=raw,unit=1,file=$efiVars"); } '' # Create a /boot EFI partition with 60M and arbitrary but fixed GUIDs for reproducibility ${pkgs.gptfdisk}/bin/sgdisk \ --set-alignment=1 --new=1:34:2047 --change-name=1:BIOSBootPartition --typecode=1:ef02 \ --set-alignment=512 --largest-new=2 --change-name=2:EFISystem --typecode=2:ef00 \ --attributes=1:set:1 \ --attributes=2:set:2 \ --disk-guid=97FD5997-D90B-4AA3-8D16-C1723AEA73C1 \ --partition-guid=1:1C06F03B-704E-4657-B9CD-681A087A2FDC \ --partition-guid=2:970C694F-AFD0-4B99-B750-CDB7A329AB6F \ --hybrid 2 \ --recompute-chs /dev/vda ${optionalString (config.boot.loader.grub.device != "/dev/vda") # In this throwaway VM, we only have the /dev/vda disk, but the # actual VM described by `config` (used by `switch-to-configuration` # below) may set `boot.loader.grub.device` to a different device # that's nonexistent in the throwaway VM. # Create a symlink for that device, so that the `grub-install` # by `switch-to-configuration` will hit /dev/vda anyway. '' ln -s /dev/vda ${config.boot.loader.grub.device} ''} ${pkgs.dosfstools}/bin/mkfs.fat -F16 /dev/vda2 export MTOOLS_SKIP_CHECK=1 ${pkgs.mtools}/bin/mlabel -i /dev/vda2 ::boot mkdir /boot mount /dev/vda2 /boot ${optionalString config.boot.loader.efi.canTouchEfiVariables '' mount -t efivarfs efivarfs /sys/firmware/efi/efivars ''} # This is needed for GRUB 0.97, which doesn't know about virtio devices. mkdir /boot/grub echo '(hd0) /dev/vda' > /boot/grub/device.map # This is needed for systemd-boot to find ESP, and udev is not available here to create this mkdir -p /dev/block ln -s /dev/vda2 /dev/block/254:2 # Install bootloader touch /etc/NIXOS export NIXOS_INSTALL_BOOTLOADER=1 ${config.system.build.toplevel}/bin/switch-to-configuration boot umount /boot '' # */ ); in { options = { virtualisation.memorySize = mkOption { default = 384; description = '' Memory size (M) of virtual machine. ''; }; virtualisation.diskSize = mkOption { default = 512; description = '' Disk size (M) of virtual machine. ''; }; virtualisation.diskImage = mkOption { default = "./${config.system.name}.qcow2"; description = '' Path to the disk image containing the root filesystem. The image will be created on startup if it does not exist. ''; }; virtualisation.bootDevice = mkOption { type = types.str; example = "/dev/vda"; description = '' The disk to be used for the root filesystem. ''; }; virtualisation.emptyDiskImages = mkOption { default = [ ]; type = types.listOf types.int; description = '' Additional disk images to provide to the VM. The value is a list of size in megabytes of each disk. These disks are writeable by the VM. ''; }; virtualisation.graphics = mkOption { default = true; description = '' Whether to run QEMU with a graphics window, or in nographic mode. Serial console will be enabled on both settings, but this will change the preferred console. ''; }; virtualisation.cores = mkOption { default = 1; type = types.int; description = '' Specify the number of cores the guest is permitted to use. The number can be higher than the available cores on the host system. ''; }; virtualisation.pathsInNixDB = mkOption { default = [ ]; description = '' The list of paths whose closure is registered in the Nix database in the VM. All other paths in the host Nix store appear in the guest Nix store as well, but are considered garbage (because they are not registered in the Nix database in the guest). ''; }; virtualisation.vlans = mkOption { default = [ 1 ]; example = [ 1 2 ]; description = '' Virtual networks to which the VM is connected. Each number N in this list causes the VM to have a virtual Ethernet interface attached to a separate virtual network on which it will be assigned IP address 192.168.N.M, where M is the index of this VM in the list of VMs. ''; }; virtualisation.writableStore = mkOption { default = true; # FIXME description = '' If enabled, the Nix store in the VM is made writable by layering an overlay filesystem on top of the host's Nix store. ''; }; virtualisation.writableStoreUseTmpfs = mkOption { default = true; description = '' Use a tmpfs for the writable store instead of writing to the VM's own filesystem. ''; }; networking.primaryIPAddress = mkOption { default = ""; internal = true; description = "Primary IP address used in /etc/hosts."; }; virtualisation.qemu = { options = mkOption { type = types.listOf types.unspecified; default = [ ]; example = [ "-vga std" ]; description = "Options passed to QEMU."; }; consoles = mkOption { type = types.listOf types.str; default = let consoles = [ "${qemuSerialDevice},115200n8" "tty0" ]; in if cfg.graphics then consoles else reverseList consoles; example = [ "console=tty1" ]; description = '' The output console devices to pass to the kernel command line via the console parameter, the primary console is the last item of this list. By default it enables both serial console and tty0. The preferred console (last one) is based on the value of . ''; }; networkingOptions = mkOption { default = [ "-net nic,netdev=user.0,model=virtio" "-netdev user,id=user.0\${QEMU_NET_OPTS:+,$QEMU_NET_OPTS}" ]; type = types.listOf types.str; description = '' Networking-related command-line options that should be passed to qemu. The default is to use userspace networking (slirp). If you override this option, be advised to keep ''${QEMU_NET_OPTS:+,$QEMU_NET_OPTS} (as seen in the default) to keep the default runtime behaviour. ''; }; drives = mkOption { type = types.listOf (types.submodule driveOpts); description = "Drives passed to qemu."; apply = addDeviceNames; }; diskInterface = mkOption { default = "virtio"; example = "scsi"; type = types.enum [ "virtio" "scsi" "ide" ]; description = "The interface used for the virtual hard disks."; }; guestAgent.enable = mkOption { default = true; type = types.bool; description = '' Enable the Qemu guest agent. ''; }; }; virtualisation.useBootLoader = mkOption { default = false; description = '' If enabled, the virtual machine will be booted using the regular boot loader (i.e., GRUB 1 or 2). This allows testing of the boot loader. If disabled (the default), the VM directly boots the NixOS kernel and initial ramdisk, bypassing the boot loader altogether. ''; }; virtualisation.useEFIBoot = mkOption { default = false; description = '' If enabled, the virtual machine will provide a EFI boot manager. useEFIBoot is ignored if useBootLoader == false. ''; }; virtualisation.efiVars = mkOption { default = "./${config.system.name}-efi-vars.fd"; description = '' Path to nvram image containing UEFI variables. The will be created on startup if it does not exist. ''; }; virtualisation.bios = mkOption { default = null; type = types.nullOr types.package; description = '' An alternate BIOS (such as qboot) with which to start the VM. Should contain a file named bios.bin. If null, QEMU's builtin SeaBIOS will be used. ''; }; }; config = { # Note [Disk layout with `useBootLoader`] # # If `useBootLoader = true`, we configure 2 drives: # `/dev/?da` for the root disk, and `/dev/?db` for the boot disk # which has the `/boot` partition and the boot loader. # Concretely: # # * The second drive's image `disk.img` is created in `bootDisk = ...` # using a throwaway VM. Note that there the disk is always `/dev/vda`, # even though in the final VM it will be at `/dev/*b`. # * The disks are attached in `virtualisation.qemu.drives`. # Their order makes them appear as devices `a`, `b`, etc. # * `fileSystems."/boot"` is adjusted to be on device `b`. # If `useBootLoader`, GRUB goes to the second disk, see # note [Disk layout with `useBootLoader`]. boot.loader.grub.device = mkVMOverride (if cfg.useBootLoader then driveDeviceName 2 # second disk else cfg.bootDevice); boot.initrd.extraUtilsCommands = '' # We need mke2fs in the initrd. copy_bin_and_libs ${pkgs.e2fsprogs}/bin/mke2fs ''; boot.initrd.postDeviceCommands = '' # If the disk image appears to be empty, run mke2fs to # initialise. FSTYPE=$(blkid -o value -s TYPE ${cfg.bootDevice} || true) if test -z "$FSTYPE"; then mke2fs -t ext4 ${cfg.bootDevice} fi ''; boot.initrd.postMountCommands = '' # Mark this as a NixOS machine. mkdir -p $targetRoot/etc echo -n > $targetRoot/etc/NIXOS # Fix the permissions on /tmp. chmod 1777 $targetRoot/tmp mkdir -p $targetRoot/boot ${optionalString cfg.writableStore '' echo "mounting overlay filesystem on /nix/store..." mkdir -p 0755 $targetRoot/nix/.rw-store/store $targetRoot/nix/.rw-store/work $targetRoot/nix/store mount -t overlay overlay $targetRoot/nix/store \ -o lowerdir=$targetRoot/nix/.ro-store,upperdir=$targetRoot/nix/.rw-store/store,workdir=$targetRoot/nix/.rw-store/work || fail ''} ''; virtualisation.bootDevice = mkDefault (driveDeviceName 1); # FIXME: Consolidate this one day. virtualisation.qemu.options = mkMerge [ (mkIf (pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64) [ "-usb" "-device usb-tablet,bus=usb-bus.0" ]) (mkIf (pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64) [ "-device virtio-gpu-pci" "-device usb-ehci,id=usb0" "-device usb-kbd" "-device usb-tablet" ]) (mkIf cfg.useEFIBoot [ "-drive if=pflash,format=raw,unit=0,readonly,file=${efiFirmware}" "-drive if=pflash,format=raw,unit=1,file=$NIX_EFI_VARS" ]) (mkIf (cfg.bios != null) [ "-bios ${cfg.bios}/bios.bin" ]) (mkIf (!cfg.graphics) [ "-nographic" ]) ]; virtualisation.qemu.drives = mkMerge [ [{ name = "root"; file = "$NIX_DISK_IMAGE"; driveExtraOpts.cache = "writeback"; driveExtraOpts.werror = "report"; }] (mkIf cfg.useBootLoader [ # The order of this list determines the device names, see # note [Disk layout with `useBootLoader`]. { name = "boot"; file = "$TMPDIR/disk.img"; driveExtraOpts.media = "disk"; deviceExtraOpts.bootindex = "1"; } ]) (imap0 (idx: _: { file = "$(pwd)/empty${toString idx}.qcow2"; driveExtraOpts.werror = "report"; }) cfg.emptyDiskImages) ]; system.build.vm = pkgs.runCommand "nixos-vm" { preferLocalBuild = true; } '' mkdir -p $out/bin ln -s ${ pkgs.writeScript "run-nixos-vm" startVM } $out/bin/run-${config.system.name}-vm ''; }; }