virtualbox: restore ability to build with Open Watcom (off by default) (#352914)

pkgs/applications/virtualization/virtualbox/default.nix

@@ -49,6 +49,9 @@
   yasm,
   glslang,
   nixosTests,
+  # If open-watcom-bin is not passed, VirtualBox will fall back to use
+  # the shipped alternative sources (assembly).
+  open-watcom-bin,
   makeself,
   perl,
   vulkan-loader,
@@ -230,11 +233,18 @@ stdenv.mkDerivation (finalAttrs: {
     })
     # While the KVM patch should not break any other behavior if --with-kvm is not specified,
     # we don't take any chances and only apply it if people actually want to use KVM support.
-    ++ optional enableKvm (fetchpatch {
-      name = "virtualbox-${finalAttrs.virtualboxVersion}-kvm-dev-${finalAttrs.kvmPatchVersion}.patch";
-      url = "https://github.com/cyberus-technology/virtualbox-kvm/releases/download/dev-${finalAttrs.kvmPatchVersion}/kvm-backend-${finalAttrs.virtualboxVersion}-dev-${finalAttrs.kvmPatchVersion}.patch";
-      hash = finalAttrs.kvmPatchHash;
-    })
+    ++ optional enableKvm (
+      let
+        patchVboxVersion =
+          # There is no updated patch for 7.0.22 yet, but the older one still applies.
+          if finalAttrs.virtualboxVersion == "7.0.22" then "7.0.20" else finalAttrs.virtualboxVersion;
+      in
+      fetchpatch {
+        name = "virtualbox-${finalAttrs.virtualboxVersion}-kvm-dev-${finalAttrs.kvmPatchVersion}.patch";
+        url = "https://github.com/cyberus-technology/virtualbox-kvm/releases/download/dev-${finalAttrs.kvmPatchVersion}/kvm-backend-${patchVboxVersion}-dev-${finalAttrs.kvmPatchVersion}.patch";
+        hash = finalAttrs.kvmPatchHash;
+      }
+    )
     ++ [
       ./qt-dependency-paths.patch
       # https://github.com/NixOS/nixpkgs/issues/123851
@@ -292,6 +302,7 @@ stdenv.mkDerivation (finalAttrs: {
       ${optionalString (!enableHardening) "--disable-hardening"} \
       ${optionalString (!enable32bitGuests) "--disable-vmmraw"} \
       ${optionalString enableWebService "--enable-webservice"} \
+      ${optionalString (open-watcom-bin != null) "--with-ow-dir=${open-watcom-bin}"} \
       ${optionalString (enableKvm) "--with-kvm"} \
       ${extraConfigureFlags} \
       --disable-kmods

pkgs/top-level/all-packages.nix

@@ -33059,6 +33059,11 @@ with pkgs;
 
     # VirtualBox uses wsimport, which was removed after JDK 8.
     jdk = jdk8;
+
+    # Opt out of building the guest BIOS sources with the problematic Open Watcom
+    # toolchain. People who need to build the BIOS from sources (for example to
+    # apply patches) can override this.
+    open-watcom-bin = null;
   };
 
   virtualboxKvm = lowPrio (virtualbox.override {