spotlights-macbook-air: Initialize muvm

hosts/linux/spotlights-macbook-air/muvm/package.nix

@@ -0,0 +1,75 @@
+{ lib
+, fetchFromGitHub
+, rustPlatform
+, dhcpcd
+, libkrun
+, makeWrapper
+, passt
+, pkg-config
+, mesa
+, replaceVars
+, systemd
+, opengl-driver ? mesa.drivers
+,
+}:
+
+rustPlatform.buildRustPackage rec {
+  pname = "muvm";
+  version = "0.3.1";
+
+  src = fetchFromGitHub {
+    owner = "AsahiLinux";
+    repo = pname;
+    rev = "muvm-${version}";
+    hash = "sha256-vacWhCiDwcRT1fNZ0oD2b1Ei2JiZSYEk3f6Mm/2jLmI=";
+  };
+
+  useFetchCargoVendor = true;
+  cargoHash = "sha256-E6p4xVdGF/ec91SE6B981IqhTQ0pNkqWozVYcY4a+tM=";
+
+  patches = [
+    (replaceVars ./replace-udevd.patch {
+      systemd-udevd = "${systemd}/lib/systemd/systemd-udevd";
+    })
+    ./replace-sysctl.patch
+    ./run-passthru.patch
+  ];
+
+  nativeBuildInputs = [
+    rustPlatform.bindgenHook
+    makeWrapper
+    pkg-config
+  ];
+
+  buildInputs = [
+    (libkrun.override {
+      withBlk = true;
+      withGpu = true;
+      withNet = true;
+    })
+    systemd
+  ];
+
+  wrapArgs = [
+    "--prefix PATH : ${
+      lib.makeBinPath [
+        passt
+        dhcpcd
+      ]
+    }"
+  ];
+
+  postFixup = ''
+    wrapProgram $out/bin/muvm $wrapArgs \
+      --set-default OPENGL_DRIVER ${opengl-driver}
+  '';
+
+  meta = {
+    description = "Run programs from your system in a microVM";
+    homepage = "https://github.com/AsahiLinux/muvm";
+    license = lib.licenses.mit;
+    maintainers = with lib.maintainers; [ RossComputerGuy ];
+    platforms = libkrun.meta.platforms;
+    mainProgram = "krun";
+  };
+}

hosts/linux/spotlights-macbook-air/muvm/replace-sysctl.patch

@@ -0,0 +1,13 @@
+diff --git a/crates/muvm/src/monitor.rs b/crates/muvm/src/monitor.rs
+index 836acd5..a7cee1c 100644
+--- a/crates/muvm/src/monitor.rs
++++ b/crates/muvm/src/monitor.rs
+@@ -49,7 +49,7 @@ fn set_guest_pressure(pressure: GuestPressure) -> Result<()> {
+     let wsf: u32 = pressure.into();
+     debug!("setting watermark_scale_factor to {wsf}");
+ 
+-    let command = PathBuf::from("/sbin/sysctl");
++    let command = PathBuf::from("sysctl");
+     let command_args = vec![format!("vm.watermark_scale_factor={}", wsf)];
+     let env = HashMap::new();
+     request_launch(command, command_args, env, 0, false, true)

hosts/linux/spotlights-macbook-air/muvm/replace-udevd.patch

@@ -0,0 +1,11 @@
+--- a/crates/muvm/src/guest/bin/muvm-guest.rs
++++ b/crates/muvm/src/guest/bin/muvm-guest.rs
+@@ -50,7 +50,7 @@ fn main() -> Result<()> {
+     rustix::stdio::dup2_stdout(console.as_fd())?;
+     rustix::stdio::dup2_stderr(console.as_fd())?;
+ 
+-    Command::new("/usr/lib/systemd/systemd-udevd").spawn()?;
++    Command::new("@systemd-udevd@").spawn()?;
+ 
+     setup_fex()?;
+ 

hosts/linux/spotlights-macbook-air/muvm/run-passthru.patch

@@ -0,0 +1,32 @@
+diff --git a/crates/muvm/src/guest/mount.rs b/crates/muvm/src/guest/mount.rs
+index 02c507d..232299b 100644
+--- a/crates/muvm/src/guest/mount.rs
++++ b/crates/muvm/src/guest/mount.rs
+@@ -14,6 +14,13 @@ use rustix::mount::{
+ use rustix::path::Arg;
+ use serde_json::json;
+ 
++/// A list of directories in /run to be passed through from the host.
++const RUN_PASSTHRU: [&str; 2] = [
++    // NixOS-specific directories.
++    "current-system",
++    "opengl-driver",
++];
++
+ fn make_tmpfs(dir: &str) -> Result<()> {
+     mount2(
+         Some("tmpfs"),
+@@ -313,6 +320,13 @@ pub fn mount_filesystems(merged_rootfs: bool) -> Result<()> {
+     )
+     .context("Failed to mount `/dev/shm`")?;
+ 
++    for dir in RUN_PASSTHRU {
++        let src = Path::new("/run/muvm-host/run").join(dir);
++        if src.exists() {
++            symlink(src, Path::new("/run").join(dir))?;
++        }
++    }
++
+     // Do this last so it can pick up all the submounts made above.
+     if let Err(e) = mount_fex_rootfs(merged_rootfs) {
+         println!("Failed to mount FEX rootfs, carrying on without. Error: {e}");