ba52ae5048
Following legacy packing conventions, `isArm` was defined just for
32-bit ARM instruction set. This is confusing to non packagers though,
because Aarch64 is an ARM instruction set.
The official ARM overview for ARMv8[1] is surprisingly not confusing,
given the overall state of affairs for ARM naming conventions, and
offers us a solution. It divides the nomenclature into three levels:
```
ISA: ARMv8 {-A, -R, -M}
/ \
Mode: Aarch32 Aarch64
| / \
Encoding: A64 A32 T32
```
At the top is the overall v8 instruction set archicture. Second are the
two modes, defined by bitwidth but differing in other semantics too, and
buttom are the encodings, (hopefully?) isomorphic if they encode the
same mode.
The 32 bit encodings are mostly backwards compatible with previous
non-Thumb and Thumb encodings, and if so we can pun the mode names to
instead mean "sets of compatable or isomorphic encodings", and then
voilà we have nice names for 32-bit and 64-bit arm instruction sets
which do not use the word ARM so as to not confused either laymen or
experienced ARM packages.
[1]: https://developer.arm.com/products/architecture/a-profile
544 lines
18 KiB
Nix
544 lines
18 KiB
Nix
# This module creates a virtual machine from the NixOS configuration.
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# Building the `config.system.build.vm' attribute gives you a command
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# that starts a KVM/QEMU VM running the NixOS configuration defined in
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# `config'. The Nix store is shared read-only with the host, which
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# makes (re)building VMs very efficient. However, it also means you
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# can't reconfigure the guest inside the guest - you need to rebuild
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# the VM in the host. On the other hand, the root filesystem is a
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# read/writable disk image persistent across VM reboots.
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{ config, lib, pkgs, ... }:
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with lib;
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with import ../../lib/qemu-flags.nix { inherit pkgs; };
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let
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qemu = config.system.build.qemu or pkgs.qemu_test;
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vmName =
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if config.networking.hostName == ""
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then "noname"
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else config.networking.hostName;
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cfg = config.virtualisation;
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qemuGraphics = if cfg.graphics then "" else "-nographic";
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kernelConsole = if cfg.graphics then "" else "console=${qemuSerialDevice}";
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ttys = [ "tty1" "tty2" "tty3" "tty4" "tty5" "tty6" ];
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# Shell script to start the VM.
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startVM =
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''
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#! ${pkgs.runtimeShell}
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NIX_DISK_IMAGE=$(readlink -f ''${NIX_DISK_IMAGE:-${config.virtualisation.diskImage}})
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if ! test -e "$NIX_DISK_IMAGE"; then
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${qemu}/bin/qemu-img create -f qcow2 "$NIX_DISK_IMAGE" \
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${toString config.virtualisation.diskSize}M || exit 1
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fi
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# Create a directory for storing temporary data of the running VM.
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if [ -z "$TMPDIR" -o -z "$USE_TMPDIR" ]; then
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TMPDIR=$(mktemp -d nix-vm.XXXXXXXXXX --tmpdir)
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fi
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# Create a directory for exchanging data with the VM.
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mkdir -p $TMPDIR/xchg
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${if cfg.useBootLoader then ''
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# Create a writable copy/snapshot of the boot disk.
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# A writable boot disk can be booted from automatically.
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${qemu}/bin/qemu-img create -f qcow2 -b ${bootDisk}/disk.img $TMPDIR/disk.img || exit 1
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${if cfg.useEFIBoot then ''
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# VM needs a writable flash BIOS.
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cp ${bootDisk}/bios.bin $TMPDIR || exit 1
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chmod 0644 $TMPDIR/bios.bin || exit 1
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'' else ''
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''}
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'' else ''
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''}
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cd $TMPDIR
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idx=2
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extraDisks=""
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${flip concatMapStrings cfg.emptyDiskImages (size: ''
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if ! test -e "empty$idx.qcow2"; then
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${qemu}/bin/qemu-img create -f qcow2 "empty$idx.qcow2" "${toString size}M"
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fi
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extraDisks="$extraDisks -drive index=$idx,file=$(pwd)/empty$idx.qcow2,if=${cfg.qemu.diskInterface},werror=report"
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idx=$((idx + 1))
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'')}
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# Start QEMU.
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exec ${qemuBinary qemu} \
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-name ${vmName} \
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-m ${toString config.virtualisation.memorySize} \
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-smp ${toString config.virtualisation.cores} \
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${concatStringsSep " " config.virtualisation.qemu.networkingOptions} \
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-virtfs local,path=/nix/store,security_model=none,mount_tag=store \
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-virtfs local,path=$TMPDIR/xchg,security_model=none,mount_tag=xchg \
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-virtfs local,path=''${SHARED_DIR:-$TMPDIR/xchg},security_model=none,mount_tag=shared \
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${if cfg.useBootLoader then ''
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-drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
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-drive index=1,id=drive2,file=$TMPDIR/disk.img,media=disk \
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${if cfg.useEFIBoot then ''
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-pflash $TMPDIR/bios.bin \
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'' else ''
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''}
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'' else ''
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-drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=${cfg.qemu.diskInterface},cache=writeback,werror=report \
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-kernel ${config.system.build.toplevel}/kernel \
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-initrd ${config.system.build.toplevel}/initrd \
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-append "$(cat ${config.system.build.toplevel}/kernel-params) init=${config.system.build.toplevel}/init regInfo=${regInfo}/registration ${kernelConsole} $QEMU_KERNEL_PARAMS" \
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''} \
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$extraDisks \
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${qemuGraphics} \
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${toString config.virtualisation.qemu.options} \
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$QEMU_OPTS \
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"$@"
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'';
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regInfo = pkgs.closureInfo { rootPaths = config.virtualisation.pathsInNixDB; };
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# Generate a hard disk image containing a /boot partition and GRUB
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# in the MBR. Used when the `useBootLoader' option is set.
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# FIXME: use nixos/lib/make-disk-image.nix.
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bootDisk =
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pkgs.vmTools.runInLinuxVM (
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pkgs.runCommand "nixos-boot-disk"
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{ preVM =
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''
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mkdir $out
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diskImage=$out/disk.img
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bootFlash=$out/bios.bin
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${qemu}/bin/qemu-img create -f qcow2 $diskImage "40M"
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${if cfg.useEFIBoot then ''
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cp ${pkgs.OVMF-CSM.fd}/FV/OVMF.fd $bootFlash
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chmod 0644 $bootFlash
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'' else ''
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''}
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'';
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buildInputs = [ pkgs.utillinux ];
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QEMU_OPTS = if cfg.useEFIBoot
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then "-pflash $out/bios.bin -nographic -serial pty"
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else "-nographic -serial pty";
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}
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''
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# Create a /boot EFI partition with 40M and arbitrary but fixed GUIDs for reproducibility
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${pkgs.gptfdisk}/bin/sgdisk \
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--set-alignment=1 --new=1:34:2047 --change-name=1:BIOSBootPartition --typecode=1:ef02 \
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--set-alignment=512 --largest-new=2 --change-name=2:EFISystem --typecode=2:ef00 \
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--attributes=1:set:1 \
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--attributes=2:set:2 \
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--disk-guid=97FD5997-D90B-4AA3-8D16-C1723AEA73C1 \
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--partition-guid=1:1C06F03B-704E-4657-B9CD-681A087A2FDC \
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--partition-guid=2:970C694F-AFD0-4B99-B750-CDB7A329AB6F \
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--hybrid 2 \
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--recompute-chs /dev/vda
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. /sys/class/block/vda2/uevent
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mknod /dev/vda2 b $MAJOR $MINOR
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. /sys/class/block/vda/uevent
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${pkgs.dosfstools}/bin/mkfs.fat -F16 /dev/vda2
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export MTOOLS_SKIP_CHECK=1
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${pkgs.mtools}/bin/mlabel -i /dev/vda2 ::boot
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# Mount /boot; load necessary modules first.
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_cp437.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/nls/nls_iso8859-1.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/fat.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/fat/vfat.ko.xz || true
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${pkgs.kmod}/bin/insmod ${pkgs.linux}/lib/modules/*/kernel/fs/efivarfs/efivarfs.ko.xz || true
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mkdir /boot
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mount /dev/vda2 /boot
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# This is needed for GRUB 0.97, which doesn't know about virtio devices.
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mkdir /boot/grub
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echo '(hd0) /dev/vda' > /boot/grub/device.map
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# Install GRUB and generate the GRUB boot menu.
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touch /etc/NIXOS
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mkdir -p /nix/var/nix/profiles
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${config.system.build.toplevel}/bin/switch-to-configuration boot
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umount /boot
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'' # */
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);
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in
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{
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imports = [ ../profiles/qemu-guest.nix ];
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options = {
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virtualisation.memorySize =
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mkOption {
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default = 384;
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description =
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''
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Memory size (M) of virtual machine.
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'';
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};
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virtualisation.diskSize =
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mkOption {
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default = 512;
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description =
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''
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Disk size (M) of virtual machine.
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'';
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};
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virtualisation.diskImage =
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mkOption {
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default = "./${vmName}.qcow2";
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description =
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''
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Path to the disk image containing the root filesystem.
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The image will be created on startup if it does not
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exist.
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'';
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};
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virtualisation.bootDevice =
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mkOption {
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type = types.str;
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example = "/dev/vda";
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description =
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''
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The disk to be used for the root filesystem.
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'';
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};
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virtualisation.emptyDiskImages =
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mkOption {
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default = [];
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type = types.listOf types.int;
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description =
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''
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Additional disk images to provide to the VM. The value is
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a list of size in megabytes of each disk. These disks are
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writeable by the VM.
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'';
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};
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virtualisation.graphics =
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mkOption {
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default = true;
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description =
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''
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Whether to run QEMU with a graphics window, or access
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the guest computer serial port through the host tty.
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'';
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};
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virtualisation.cores =
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mkOption {
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default = 1;
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type = types.int;
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description =
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''
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Specify the number of cores the guest is permitted to use.
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The number can be higher than the available cores on the
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host system.
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'';
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};
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virtualisation.pathsInNixDB =
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mkOption {
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default = [];
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description =
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''
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The list of paths whose closure is registered in the Nix
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database in the VM. All other paths in the host Nix store
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appear in the guest Nix store as well, but are considered
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garbage (because they are not registered in the Nix
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database in the guest).
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'';
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};
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virtualisation.vlans =
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mkOption {
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default = [ 1 ];
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example = [ 1 2 ];
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description =
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''
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Virtual networks to which the VM is connected. Each
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number <replaceable>N</replaceable> in this list causes
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the VM to have a virtual Ethernet interface attached to a
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separate virtual network on which it will be assigned IP
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address
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<literal>192.168.<replaceable>N</replaceable>.<replaceable>M</replaceable></literal>,
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where <replaceable>M</replaceable> is the index of this VM
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in the list of VMs.
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'';
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};
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virtualisation.writableStore =
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mkOption {
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default = true; # FIXME
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description =
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''
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If enabled, the Nix store in the VM is made writable by
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layering an overlay filesystem on top of the host's Nix
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store.
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'';
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};
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virtualisation.writableStoreUseTmpfs =
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mkOption {
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default = true;
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description =
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''
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Use a tmpfs for the writable store instead of writing to the VM's
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own filesystem.
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'';
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};
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networking.primaryIPAddress =
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mkOption {
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default = "";
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internal = true;
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description = "Primary IP address used in /etc/hosts.";
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};
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virtualisation.qemu = {
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options =
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mkOption {
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type = types.listOf types.unspecified;
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default = [];
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example = [ "-vga std" ];
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description = "Options passed to QEMU.";
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};
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networkingOptions =
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mkOption {
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default = [
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"-net nic,netdev=user.0,model=virtio"
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"-netdev user,id=user.0\${QEMU_NET_OPTS:+,$QEMU_NET_OPTS}"
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];
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type = types.listOf types.str;
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description = ''
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Networking-related command-line options that should be passed to qemu.
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The default is to use userspace networking (slirp).
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If you override this option, be advised to keep
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''${QEMU_NET_OPTS:+,$QEMU_NET_OPTS} (as seen in the default)
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to keep the default runtime behaviour.
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'';
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};
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diskInterface =
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mkOption {
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default = "virtio";
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example = "scsi";
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type = types.str;
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description = ''
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The interface used for the virtual hard disks
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(<literal>virtio</literal> or <literal>scsi</literal>).
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'';
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};
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};
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virtualisation.useBootLoader =
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mkOption {
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default = false;
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description =
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''
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If enabled, the virtual machine will be booted using the
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regular boot loader (i.e., GRUB 1 or 2). This allows
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testing of the boot loader. If
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disabled (the default), the VM directly boots the NixOS
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kernel and initial ramdisk, bypassing the boot loader
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altogether.
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'';
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};
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virtualisation.useEFIBoot =
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mkOption {
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default = false;
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description =
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''
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If enabled, the virtual machine will provide a EFI boot
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manager.
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useEFIBoot is ignored if useBootLoader == false.
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'';
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};
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};
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config = {
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boot.loader.grub.device = mkVMOverride cfg.bootDevice;
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boot.initrd.extraUtilsCommands =
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''
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# We need mke2fs in the initrd.
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copy_bin_and_libs ${pkgs.e2fsprogs}/bin/mke2fs
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'';
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boot.initrd.postDeviceCommands =
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''
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# If the disk image appears to be empty, run mke2fs to
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# initialise.
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FSTYPE=$(blkid -o value -s TYPE ${cfg.bootDevice} || true)
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if test -z "$FSTYPE"; then
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mke2fs -t ext4 ${cfg.bootDevice}
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fi
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'';
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boot.initrd.postMountCommands =
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''
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# Mark this as a NixOS machine.
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mkdir -p $targetRoot/etc
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echo -n > $targetRoot/etc/NIXOS
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# Fix the permissions on /tmp.
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chmod 1777 $targetRoot/tmp
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mkdir -p $targetRoot/boot
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${optionalString cfg.writableStore ''
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echo "mounting overlay filesystem on /nix/store..."
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mkdir -p 0755 $targetRoot/nix/.rw-store/store $targetRoot/nix/.rw-store/work $targetRoot/nix/store
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mount -t overlay overlay $targetRoot/nix/store \
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-o lowerdir=$targetRoot/nix/.ro-store,upperdir=$targetRoot/nix/.rw-store/store,workdir=$targetRoot/nix/.rw-store/work || fail
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''}
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'';
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# After booting, register the closure of the paths in
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# `virtualisation.pathsInNixDB' in the Nix database in the VM. This
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# allows Nix operations to work in the VM. The path to the
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# registration file is passed through the kernel command line to
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# allow `system.build.toplevel' to be included. (If we had a direct
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# reference to ${regInfo} here, then we would get a cyclic
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# dependency.)
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boot.postBootCommands =
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''
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if [[ "$(cat /proc/cmdline)" =~ regInfo=([^ ]*) ]]; then
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${config.nix.package.out}/bin/nix-store --load-db < ''${BASH_REMATCH[1]}
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fi
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'';
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boot.initrd.availableKernelModules =
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optional cfg.writableStore "overlay"
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++ optional (cfg.qemu.diskInterface == "scsi") "sym53c8xx";
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virtualisation.bootDevice =
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mkDefault (if cfg.qemu.diskInterface == "scsi" then "/dev/sda" else "/dev/vda");
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virtualisation.pathsInNixDB = [ config.system.build.toplevel ];
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# FIXME: Consolidate this one day.
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virtualisation.qemu.options = mkMerge [
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(mkIf (pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64) [ "-vga std" "-usb" "-device usb-tablet,bus=usb-bus.0" ])
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(mkIf (pkgs.stdenv.isAarch32 || pkgs.stdenv.isAarch64) [ "-device virtio-gpu-pci" "-device usb-ehci,id=usb0" "-device usb-kbd" "-device usb-tablet" ])
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];
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# Mount the host filesystem via 9P, and bind-mount the Nix store
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# of the host into our own filesystem. We use mkVMOverride to
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# allow this module to be applied to "normal" NixOS system
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# configuration, where the regular value for the `fileSystems'
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# attribute should be disregarded for the purpose of building a VM
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# test image (since those filesystems don't exist in the VM).
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fileSystems = mkVMOverride (
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{ "/".device = cfg.bootDevice;
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${if cfg.writableStore then "/nix/.ro-store" else "/nix/store"} =
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{ device = "store";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" "cache=loose" ];
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neededForBoot = true;
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};
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"/tmp" = mkIf config.boot.tmpOnTmpfs
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{ device = "tmpfs";
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fsType = "tmpfs";
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neededForBoot = true;
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# Sync with systemd's tmp.mount;
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options = [ "mode=1777" "strictatime" "nosuid" "nodev" ];
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};
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"/tmp/xchg" =
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{ device = "xchg";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" "cache=loose" ];
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neededForBoot = true;
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};
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"/tmp/shared" =
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{ device = "shared";
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fsType = "9p";
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options = [ "trans=virtio" "version=9p2000.L" ];
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neededForBoot = true;
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};
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|
} // optionalAttrs (cfg.writableStore && cfg.writableStoreUseTmpfs)
|
|
{ "/nix/.rw-store" =
|
|
{ fsType = "tmpfs";
|
|
options = [ "mode=0755" ];
|
|
neededForBoot = true;
|
|
};
|
|
} // optionalAttrs cfg.useBootLoader
|
|
{ "/boot" =
|
|
{ device = "/dev/vdb2";
|
|
fsType = "vfat";
|
|
options = [ "ro" ];
|
|
noCheck = true; # fsck fails on a r/o filesystem
|
|
};
|
|
});
|
|
|
|
swapDevices = mkVMOverride [ ];
|
|
boot.initrd.luks.devices = mkVMOverride {};
|
|
|
|
# Don't run ntpd in the guest. It should get the correct time from KVM.
|
|
services.timesyncd.enable = false;
|
|
|
|
system.build.vm = pkgs.runCommand "nixos-vm" { preferLocalBuild = true; }
|
|
''
|
|
mkdir -p $out/bin
|
|
ln -s ${config.system.build.toplevel} $out/system
|
|
ln -s ${pkgs.writeScript "run-nixos-vm" startVM} $out/bin/run-${vmName}-vm
|
|
'';
|
|
|
|
# When building a regular system configuration, override whatever
|
|
# video driver the host uses.
|
|
services.xserver.videoDrivers = mkVMOverride [ "modesetting" ];
|
|
services.xserver.defaultDepth = mkVMOverride 0;
|
|
services.xserver.resolutions = mkVMOverride [ { x = 1024; y = 768; } ];
|
|
services.xserver.monitorSection =
|
|
''
|
|
# Set a higher refresh rate so that resolutions > 800x600 work.
|
|
HorizSync 30-140
|
|
VertRefresh 50-160
|
|
'';
|
|
|
|
# Wireless won't work in the VM.
|
|
networking.wireless.enable = mkVMOverride false;
|
|
networking.connman.enable = mkVMOverride false;
|
|
|
|
# Speed up booting by not waiting for ARP.
|
|
networking.dhcpcd.extraConfig = "noarp";
|
|
|
|
networking.usePredictableInterfaceNames = false;
|
|
|
|
system.requiredKernelConfig = with config.lib.kernelConfig;
|
|
[ (isEnabled "VIRTIO_BLK")
|
|
(isEnabled "VIRTIO_PCI")
|
|
(isEnabled "VIRTIO_NET")
|
|
(isEnabled "EXT4_FS")
|
|
(isYes "BLK_DEV")
|
|
(isYes "PCI")
|
|
(isYes "EXPERIMENTAL")
|
|
(isYes "NETDEVICES")
|
|
(isYes "NET_CORE")
|
|
(isYes "INET")
|
|
(isYes "NETWORK_FILESYSTEMS")
|
|
] ++ optional (!cfg.graphics) [
|
|
(isYes "SERIAL_8250_CONSOLE")
|
|
(isYes "SERIAL_8250")
|
|
];
|
|
|
|
};
|
|
}
|