grub: build grub2_pvhgrub_image together with grub2_pvgrub_image

This enables the GRUB package to be built for the `xen_pvh` platform, which is
needed to generate a corresponding GRUB image and boot PVH DomUs.

Also, modifications made to the original `grub2_pvgrub_image` package:
- Use split phases and avoid overriding `buildCommand` during the build.
- Remove logic that excludes `all_video.mod` (already ironed out by upstream).
- Fix `lib.platforms` and remove platforms that cannot build.
- Update the description.
- Add maintainer information of the Xen Project team.

Signed-off-by: Hongbo <hehongbo@mail.com>
Reviewed-by: Fernando Rodrigues <alpha@sigmasquadron.net>
Co-authored-by: William Johansson <radar@radhuset.org>

pkgs/by-name/gr/grub2_pvgrub_image/package.nix

@@ -1,54 +0,0 @@
-{
-  lib,
-  stdenv,
-  grub2_xen,
-}:
-
-let
-  efiSystemsBuild = {
-    i686-linux.target = "i386";
-    x86_64-linux.target = "x86_64";
-    armv7l-linux.target = "arm";
-    aarch64-linux.target = "aarch64";
-    riscv32-linux.target = "riscv32";
-    riscv64-linux.target = "riscv64";
-  };
-
-in
-(
-
-  stdenv.mkDerivation rec {
-    name = "pvgrub-image";
-
-    configs = ./configs;
-
-    buildInputs = [ grub2_xen ];
-
-    buildCommand = ''
-      cp "${configs}"/* .
-      tar -cf memdisk.tar grub.cfg
-      # We include all modules except all_video.mod as otherwise grub will fail printing "no symbol table"
-      # if we include it.
-      grub-mkimage -O "${
-        efiSystemsBuild.${stdenv.hostPlatform.system}.target
-      }-xen" -c grub-bootstrap.cfg \
-        -m memdisk.tar -o "grub-${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen.bin" \
-        $(ls "${grub2_xen}/lib/grub/${
-          efiSystemsBuild.${stdenv.hostPlatform.system}.target
-        }-xen/" |grep 'mod''$'|grep -v '^all_video\.mod''$')
-      mkdir -p "$out/lib/grub-xen"
-      cp "grub-${efiSystemsBuild.${stdenv.hostPlatform.system}.target}-xen.bin" $out/lib/grub-xen/
-    '';
-
-    meta = with lib; {
-      description = "PvGrub image for use for booting PV Xen guests";
-
-      longDescription = ''
-        This package provides a PvGrub image for booting Para-Virtualized (PV)
-        Xen guests
-      '';
-
-      platforms = platforms.gnu ++ platforms.linux;
-    };
-  }
-)

pkgs/by-name/gr/grub2_pvhgrub_image/package.nix

@@ -0,0 +1,83 @@
+{
+  lib,
+  stdenv,
+  grub2_xen,
+  grub2_xen_pvh,
+  grubPlatform ? "xen_pvh",
+}:
+
+assert lib.assertOneOf "grubPlatform" grubPlatform [
+  "xen"
+  "xen_pvh"
+];
+let
+  targets = {
+    i686-linux.target = "i386";
+    x86_64-linux.target = if grubPlatform == "xen_pvh" then "i386" else "x86_64";
+  };
+in
+stdenv.mkDerivation {
+  name = "grub2_${grubPlatform}_image";
+
+  env = {
+    GRUB_CONFIGS = "${./configs}";
+    GRUB_FORMAT = "${targets.${stdenv.buildPlatform.system}.target}-${grubPlatform}";
+  };
+
+  buildInputs =
+    lib.optional (grubPlatform == "xen") grub2_xen
+    ++ lib.optional (grubPlatform == "xen_pvh") grub2_xen_pvh;
+
+  dontUnpack = true;
+
+  buildPhase = ''
+    cp "$GRUB_CONFIGS"/* .
+    tar -cf memdisk.tar grub.cfg
+    grub-mkimage \
+      -O "$GRUB_FORMAT" \
+      -c grub-bootstrap.cfg \
+      -m memdisk.tar \
+      -o grub-"$GRUB_FORMAT".bin \
+      ${if grubPlatform == "xen_pvh" then grub2_xen_pvh else grub2_xen}/lib/grub/"$GRUB_FORMAT"/*.mod
+  '';
+
+  installPhase = ''
+    mkdir -p "$out/lib/grub-${grubPlatform}"
+    cp grub-"$GRUB_FORMAT".bin $out/lib/grub-${grubPlatform}/
+  '';
+
+  dontFixup = true;
+
+  meta = {
+    description = "PvGrub2 image for booting ${
+      if grubPlatform == "xen_pvh" then "PVH" else "PV"
+    } Xen guests";
+
+    longDescription =
+      if (grubPlatform == "xen_pvh") then
+        ''
+          This package provides a prebuilt PvGrub2 image for booting PVH Xen
+          guests (also commonly referred to as PvhGrub2), which searches for
+          `grub.cfg` on the guest disk and interprets it to load the kernel,
+          eliminating the need to copy the guest kernel to the Dom0.
+
+          You will need `pkgs.grub2_xen_pvh` to build a customized PvhGrub2
+          image. See [PvGrub2](https://wiki.xenproject.org/wiki/PvGrub2) for
+          more explanations.
+        ''
+      else
+        ''
+          This package provides a prebuilt PvGrub2 image for booting PV Xen
+          guests, which searches for `grub.cfg` on the guest disk and interprets
+          it to load the kernel, eliminating the need to copy the guest kernel
+          to the Dom0.
+
+          You will need `pkgs.grub2_xen` to build a customized PvGrub2 image.
+          See [PvGrub2](https://wiki.xenproject.org/wiki/PvGrub2) for more
+          explanations.
+        '';
+
+    teams = [ lib.teams.xen ];
+    platforms = lib.attrNames targets;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -3142,6 +3142,10 @@ with pkgs;
     xenPvhSupport = true;
   };
 
+  grub2_pvgrub_image = grub2_pvhgrub_image.override {
+    grubPlatform = "xen";
+  };
+
   grub4dos = callPackage ../tools/misc/grub4dos {
     stdenv = stdenv_32bit;
   };