feat: FAST looking glass! TONS of time on this jesus christ

nixos/libvirtd.nix

@@ -0,0 +1,46 @@
+{ lib, pkgs, config, ... }:
+with lib;
+let
+  cfg = config.virtualisation.libvirtd;
+
+  aclString = with lib.strings;
+    concatMapStringsSep ''
+      ,
+        '' escapeNixString cfg.deviceACL;
+in {
+  options.virtualisation.libvirtd = {
+    deviceACL = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      description = "allowed devices";
+    };
+  };
+
+  # All this was part of the rabbit hole of getting looking glass working properly
+  # This below also seems very important
+  # https://forum.level1techs.com/t/new-looking-glass-beta-7-release-candidate-1/208250
+  # same here, wrt cpu max bits possibly preventing shared memory from working
+  # https://forum.level1techs.com/t/looking-glass-b6-and-b7-rc1-not-working-with-new-kernels/222134/7
+  # https://www.kraxel.org/blog/2023/12/qemu-phys-bits/
+  # https://libvirt.org/formatdomain.html#cpu-model-and-topology
+  # 
+  # Needed to make sure to pass
+  # all these different /dev/'s, otherwise qemu won't be able to
+  # start properly. I'm not 100% on either where the user here
+  # got this list, nor which i actually *need*, but either way
+  # this was an immense help:
+  # https://forum.level1techs.com/t/solved-unable-to-connect-to-libvirt-qemu-system-after-changing-to-kernel-module/219006
+
+  # 
+  config.virtualisation.libvirtd.qemu.verbatimConfig = ''
+    namespaces = []
+
+    cgroup_device_acl = [
+      "/dev/null", "/dev/full", "/dev/zero",
+      "/dev/random", "/dev/urandom",
+      "/dev/ptmx", "/dev/kvm",
+      "/dev/userfaultfd",
+      ${aclString}
+    ]
+  '';
+}