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nixos/qemu-vm: fix diskless VMs #228047

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Merged
RaitoBezarius merged 1 commit into from
May 5, 2023
Merged

nixos/qemu-vm: fix diskless VMs #228047

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27 changes: 19 additions & 8 deletions nixos/modules/virtualisation/qemu-vm.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -264,7 +264,7 @@ let
suggestedRootDevice = {
"efi_bootloading_with_default_fs" = "${cfg.bootLoaderDevice}2";
"legacy_bootloading_with_default_fs" = "${cfg.bootLoaderDevice}1";
"direct_boot_with_default_fs" = cfg.bootLoaderDevice;
"direct_boot_with_default_fs" = lookupDriveDeviceName "root" cfg.qemu.drives;
# This will enforce a NixOS module type checking error
# to ask explicitly the user to set a rootDevice.
# As it will look like `rootDevice = lib.mkDefault null;` after
Expand Down Expand Up @@ -336,14 +336,14 @@ in

virtualisation.bootLoaderDevice =
mkOption {
type = types.path;
default = lookupDriveDeviceName "root" cfg.qemu.drives;
defaultText = literalExpression ''lookupDriveDeviceName "root" cfg.qemu.drives'';
type = types.nullOr types.path;
default = if cfg.useBootLoader then lookupDriveDeviceName "root" cfg.qemu.drives else null;
defaultText = literalExpression ''if cfg.useBootLoader then lookupDriveDeviceName "root" cfg.qemu.drives else null;'';
example = "/dev/vda";
description =
lib.mdDoc ''
The disk to be used for the boot filesystem.
By default, it is the same disk as the root filesystem.
By default, it is the same disk as the root filesystem if you use a bootloader, otherwise it's null.
'';
};

Expand Down Expand Up @@ -836,6 +836,16 @@ in
Invalid virtualisation.forwardPorts.<entry ${toString i}>.guest.address:
The address must be in the default VLAN (10.0.2.0/24).
'';
}
{ assertion = cfg.useBootLoader -> cfg.diskImage != null;
message =
''
Currently, bootloaders cannot be used with a tmpfs disk image.
It would require some rework in the boot configuration mechanism
to detect the proper boot partition in UEFI scenarios for example.

If you are interested into this feature, please open an issue or open a pull request.
'';
}
]));

Expand Down Expand Up @@ -863,21 +873,22 @@ in
# legacy and UEFI. In order to avoid this, we have to put "nodev" to force UEFI-only installs.
# Otherwise, we set the proper bootloader device for this.
# FIXME: make a sense of this mess wrt to multiple ESP present in the system, probably use boot.efiSysMountpoint?
boot.loader.grub.device = mkVMOverride (if cfg.useEFIBoot then "nodev" else cfg.bootLoaderDevice);
boot.loader.grub.enable = cfg.useBootLoader;
boot.loader.grub.device = mkIf cfg.useBootLoader (mkVMOverride (if cfg.useEFIBoot then "nodev" else cfg.bootLoaderDevice));
boot.loader.grub.gfxmodeBios = with cfg.resolution; "${toString x}x${toString y}";
virtualisation.rootDevice = mkDefault suggestedRootDevice;

boot.initrd.kernelModules = optionals (cfg.useNixStoreImage && !cfg.writableStore) [ "erofs" ];

boot.loader.supportsInitrdSecrets = mkIf (!cfg.useBootLoader) (mkVMOverride false);

boot.initrd.extraUtilsCommands = lib.mkIf (cfg.useDefaultFilesystems && !config.boot.initrd.systemd.enable)
boot.initrd.extraUtilsCommands = lib.mkIf (cfg.useDefaultFilesystems && !config.boot.initrd.systemd.enable && cfg.diskImage != null)
''
# We need mke2fs in the initrd.
copy_bin_and_libs ${pkgs.e2fsprogs}/bin/mke2fs
'';

boot.initrd.postDeviceCommands = lib.mkIf (cfg.useDefaultFilesystems && !config.boot.initrd.systemd.enable)
boot.initrd.postDeviceCommands = lib.mkIf (cfg.useDefaultFilesystems && !config.boot.initrd.systemd.enable && cfg.diskImage != null)
''
# If the disk image appears to be empty, run mke2fs to
# initialise.
Expand Down