···

       
1
       
1
       
 
       
# This module creates a virtual machine from the NixOS configuration.

     

       
2
       
2
       
 
       
# Building the `config.system.build.vm' attribute gives you a command

     

       
3
       
3
       
 
       
# that starts a KVM/QEMU VM running the NixOS configuration defined in

     

       
4
       
4
       
-
       
# `config'.  The Nix store is shared read-only with the host, which

     

       
5
       
5
       
-
       
# makes (re)building VMs very efficient.  However, it also means you

     

       
6
       
6
       
-
       
# can't reconfigure the guest inside the guest - you need to rebuild

     

       
7
       
7
       
-
       
# the VM in the host.  On the other hand, the root filesystem is a

     

       
8
       
8
       
-
       
# read/writable disk image persistent across VM reboots.

     

       
4
       
4
       
+
       
# `config'. By default, the Nix store is shared read-only with the

     

       
5
       
5
       
+
       
# host, which makes (re)building VMs very efficient.

     

       
9
       
6
       
 
       


     

       
10
       
7
       
 
       
{ config, lib, pkgs, options, ... }:

     

       
11
       
8
       
 
       


     
···

       
778
       
775
       
 
       
        default = false;

     

       
779
       
776
       
 
       
        description =

     

       
780
       
777
       
 
       
          lib.mdDoc ''

     

       
781
       
781
       
-
       
            If enabled, the virtual machine will be booted using the

     

       
782
       
782
       
-
       
            regular boot loader (i.e., GRUB 1 or 2).  This allows

     

       
783
       
783
       
-
       
            testing of the boot loader.  If

     

       
784
       
784
       
-
       
            disabled (the default), the VM directly boots the NixOS

     

       
785
       
785
       
-
       
            kernel and initial ramdisk, bypassing the boot loader

     

       
786
       
786
       
-
       
            altogether.

     

       
778
       
778
       
+
       
            Use a boot loader to boot the system.

     

       
779
       
779
       
+
       
            This allows, among other things, testing the boot loader.

     

       
780
       
780
       
+
       


     

       
781
       
781
       
+
       
            If disabled, the kernel and initrd are directly booted,

     

       
782
       
782
       
+
       
            forgoing any bootloader.

     

       
787
       
783
       
 
       
          '';

     

       
788
       
784
       
 
       
      };

     

       
789
       
785
       
 
       


     
···

       
1026
       
1022
       
 
       
        "-netdev user,id=user.0,${forwardingOptions}${restrictNetworkOption}\"$QEMU_NET_OPTS\""

     

       
1027
       
1023
       
 
       
      ];

     

       
1028
       
1024
       
 
       


     

       
1029
       
1029
       
-
       
    # FIXME: Consolidate this one day.

     

       
1030
       
1025
       
 
       
    virtualisation.qemu.options = mkMerge [

     

       
1031
       
1026
       
 
       
      (mkIf cfg.qemu.virtioKeyboard [

     

       
1032
       
1027
       
 
       
        "-device virtio-keyboard"

     
···

       
1078
       
1073
       
 
       
      }) cfg.emptyDiskImages)

     

       
1079
       
1074
       
 
       
    ];

     

       
1080
       
1075
       
 
       


     

       
1076
       
1076
       
+
       
    # Use mkVMOverride to enable building test VMs (e.g. via `nixos-rebuild

     

       
1077
       
1077
       
+
       
    # build-vm`) of a system configuration, where the regular value for the

     

       
1078
       
1078
       
+
       
    # `fileSystems' attribute should be disregarded (since those filesystems

     

       
1079
       
1079
       
+
       
    # don't necessarily exist in the VM).

     

       
1081
       
1080
       
 
       
    fileSystems = mkVMOverride cfg.fileSystems;

     

       
1082
       
1081
       
 
       


     

       
1083
       
1083
       
-
       
    # Mount the host filesystem via 9P, and bind-mount the Nix store

     

       
1084
       
1084
       
-
       
    # of the host into our own filesystem.  We use mkVMOverride to

     

       
1085
       
1085
       
-
       
    # allow this module to be applied to "normal" NixOS system

     

       
1086
       
1086
       
-
       
    # configuration, where the regular value for the `fileSystems'

     

       
1087
       
1087
       
-
       
    # attribute should be disregarded for the purpose of building a VM

     

       
1088
       
1088
       
-
       
    # test image (since those filesystems don't exist in the VM).

     

       
1089
       
1082
       
 
       
    virtualisation.fileSystems = let

     

       
1090
       
1083
       
 
       
      mkSharedDir = tag: share:

     

       
1091
       
1084
       
 
       
        {