flake.nix: add a way to build Linux images

This isn't hooked up to the images that end up on the TS downloads
(yet, could be done in the future).

However, it is pretty convenient to have a way to easily reproduce
the images that we host and at least we could test that it all builds.

Signed-off-by: Ivan Velickovic <i.velickovic@unsw.edu.au>

Author: Ivan-Velickovic

.github/workflows/ci.yaml

@@ -42,6 +42,17 @@ jobs:
           name: MANUAL
           path: docs/MANUAL.pdf
 
+  build_guest_images:
+    name: Build guest images (Nix)
+    runs-on: [self-hosted, Linux, X64]
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+      - name: Setup Nix
+        uses: cachix/install-nix-action@v27
+      - name: Build guest images
+        run: nix build .#images
+
   build_macos_arm64:
     name: Build examples (macOS ARM64)
     runs-on: macos-14

.gitignore

@@ -13,3 +13,4 @@ rust/target/
 compile_commands.json
 *.orig
 __pycache__/
+result

flake.nix

@@ -34,6 +34,60 @@
       forAllSystems = with nixpkgs.lib; genAttrs (builtins.attrNames microkit-platforms);
     in
     {
+      packages = forAllSystems (
+        system:
+        let
+          pkgs = import nixpkgs {
+            inherit system;
+          };
+
+          linux-613 = pkgs.fetchFromGitHub {
+            owner = "torvalds";
+            repo = "linux";
+            rev = "v6.13";
+            hash = "sha256-FD22KmTFrIhED5X3rcjPTot1UOq1ir1zouEpRWZkRC0=";
+          };
+
+          linux-518 = pkgs.fetchFromGitHub {
+            owner = "torvalds";
+            repo = "linux";
+            rev = "v5.18";
+            hash = "sha256-EB4nc9eHNAY2bHZVAnTckh/WpUkZN5EUj3rXZFR0E0M=";
+          };
+
+          linux-aarch64-example-simple = (pkgs.pkgsCross.aarch64-multiplatform.callPackage ./tools/linux/linux.nix {}) {
+            version = "5.18";
+            src = linux-518;
+            arch = "arm64";
+            configFile = ./examples/simple/images/linux_config;
+          };
+
+          linux-aarch64-example-virtio = (pkgs.pkgsCross.aarch64-multiplatform.callPackage ./tools/linux/linux.nix {}) {
+            version = "6.13";
+            src = linux-613;
+            arch = "arm64";
+            configFile = ./examples/virtio/client_vm/linux_config;
+          };
+
+          allImages = pkgs.runCommand "all-images" { nativeBuildInputs = with pkgs; [ gnutar gzip ]; }
+            ''
+              mkdir -p $out
+
+              mkdir -p $out/linux-aarch64-example-simple/
+              cp ${linux-aarch64-example-simple}/* $out/linux-aarch64-example-simple/
+
+              mkdir -p $out/linux-aarch64-example-virtio/
+              cp ${linux-aarch64-example-virtio}/* $out/linux-aarch64-example-virtio/
+
+              cd $out
+              for f in linux-*; do tar cf - $f | gzip -9 > `basename $f`.tar.gz; done
+            ''
+          ;
+        in
+        {
+          images = allImages;
+        }
+      );
       devShells = forAllSystems (
         system:
         let

tools/linux/linux.nix

@@ -0,0 +1,113 @@
+{
+  stdenv,
+  lib,
+  elfutils,
+  bc,
+  bison,
+  dtc,
+  fetchFromGitHub,
+  fetchpatch,
+  fetchurl,
+  flex,
+  perl,
+  gnutls,
+  installShellFiles,
+  libuuid,
+  meson-tools,
+  ncurses,
+  openssl,
+  python3,
+  pkg-config,
+  which,
+  buildPackages,
+  callPackages,
+}@pkgs:
+
+  lib.makeOverridable (
+    {
+      arch,
+      version,
+      src,
+      installDir ? "$out",
+      configFile,
+      extraPatches ? [ ],
+      extraMakeFlags ? [ ],
+      stdenv ? pkgs.stdenv,
+      # TODO: actually implement
+      extraFilesToInstall ? [ ],
+      ...
+    }@args:
+    stdenv.mkDerivation (
+      {
+        inherit version src;
+
+        pname = "linux-${arch}-${configFile}";
+
+        patches = extraPatches;
+
+        # postPatch = ''
+        #   ${lib.concatMapStrings (script: ''
+        #     substituteInPlace ${script} \
+        #     --replace "#!/usr/bin/env python3" "#!${pythonScriptsToInstall.${script}}/bin/python3"
+        #   '') (builtins.attrNames pythonScriptsToInstall)}
+        #   patchShebangs tools
+        #   patchShebangs scripts
+        # '';
+
+        nativeBuildInputs = [
+          ncurses # tools/kwboot
+          perl
+          bc
+          bison
+          openssl
+          pkg-config
+          flex
+          installShellFiles
+          python3
+          which
+          elfutils
+        ];
+        depsBuildBuild = [ buildPackages.gccStdenv.cc ]; # gccStdenv is needed for Darwin buildPlatform
+
+        hardeningDisable = [ "all" ];
+
+        enableParallelBuilding = true;
+
+        makeFlags = [
+          "ARCH=${arch}"
+          "DTC=${lib.getExe buildPackages.dtc}"
+          "CROSS_COMPILE=${stdenv.cc.targetPrefix}"
+          "HOSTCFLAGS=-fcommon"
+        ]
+        ++ extraMakeFlags;
+
+        passAsFile = [ "extraConfig" ];
+
+        configurePhase = ''
+          runHook preConfigure
+
+          cp ${configFile} .config
+          make $makeFlags -j$NIX_BUILD_CORES
+
+          runHook postConfigure
+        '';
+
+        installPhase = ''
+          runHook preInstall
+
+          mkdir -p ${installDir}
+          cp .config ${installDir}/config
+          cp vmlinux ${installDir}
+          ls -l arch/${arch}/boot/Image && cp arch/${arch}/boot/Image ${installDir}
+          ls -l arch/${arch}/boot/Image.gz && cp arch/${arch}/boot/Image.gz ${installDir}
+          ls -l arch/${arch}/boot/bzImage && cp arch/${arch}/boot/bzImage ${installDir}
+
+          runHook postInstall
+        '';
+
+        dontStrip = true;
+
+      }
+    )
+  )
+