100 lines
2.5 KiB
Org Mode
100 lines
2.5 KiB
Org Mode
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#+title: QEMU
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#+setupfile: ../headers
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* QEMU
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On machines where I run virtual machines, I want =virt-manager=,
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=libvirtd=, and a few supporting pieces set up together. Here’s the
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skeleton of the =nixos.qemu= module.
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#+begin_src nix :tangle yes
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{
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flake.modules.nixos.qemu = {
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config,
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lib,
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pkgs,
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...
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}:
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with lib; let
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cfg = config.mySystem.dev.qemu;
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in {
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<<options>>
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config = {
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<<virt-manager>>
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<<libvirtd-group>>
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<<virtualisation>>
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<<packages>>
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<<firmware-tmpfiles>>
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<<binfmt>>
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};
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};
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}
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#+end_src
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** Declaring the Options
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=users= lists which users get added to the =libvirtd= group, so they can
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manage VMs without needing root. By default, I add myself to this
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group.
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#+name: options
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#+begin_src nix
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options.mySystem.dev.qemu.users = mkOption {
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type = types.listOf types.str;
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default = ["phundrak"];
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example = ["user1" "user2"];
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};
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#+end_src
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This option is then passed onto the standard NixOS option.
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#+name: libvirtd-group
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#+begin_src nix
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users.groups.libvirtd.members = cfg.users;
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#+end_src
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** virt-manager
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This pulls in the GUI I actually use to create and manage VMs.
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#+name: virt-manager
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#+begin_src nix
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programs.virt-manager.enable = true;
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#+end_src
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** Virtualisation Backend
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=libvirtd= is the daemon that actually runs and manages the VMs. SPICE
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USB redirection lets me pass a USB device straight through to a guest
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without unplugging it from the host first.
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#+name: virtualisation
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#+begin_src nix
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virtualisation = {
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libvirtd.enable = true;
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spiceUSBRedirection.enable = true;
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};
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#+end_src
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** Extra Packages
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Besides =qemu= itself, =quickemu= lets me spin up a VM from a template in
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one command, and =swtpm= provides the software TPM that guests like
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Windows 11 insist on.
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#+name: packages
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#+begin_src nix
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environment.systemPackages = with pkgs; [
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qemu
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quickemu
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swtpm
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];
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#+end_src
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** Firmware Lookup Path
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=virt-manager= and friends expect to find UEFI firmware images under
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=/var/lib/qemu/firmware=, so I symlink QEMU’s own copy there instead of
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making every tool aware of the Nix store path.
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#+name: firmware-tmpfiles
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#+begin_src nix
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systemd.tmpfiles.rules = ["L+ /var/lib/qemu/firmware - - - - ${pkgs.qemu}/share/qemu/firmware"];
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#+end_src
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** ARM Emulation
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This lets me run (and build) =aarch64-linux= binaries transparently
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through QEMU’s user-mode emulation, which comes in handy when working
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on the PineTab2 without needing actual ARM hardware on hand.
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#+name: binfmt
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#+begin_src nix
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boot.binfmt.emulatedSystems = ["aarch64-linux"];
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#+end_src
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