Look in known directories for OVMF

Rsconscript

@@ -1,6 +1,7 @@
 configure do
   check_program "mformat"
   check_program "x86_64-w64-mingw32-gcc"
+  check_cfg package: "gnu-efi", use: false
 end
 
 class Image < Builder
@@ -31,5 +32,11 @@ uefi_env = env "uefi" do |env|
 end
 
 task "run" do
-	sh %W[qemu-system-x86_64 -bios OVMF.fd -drive file=#{uefi_env.expand("^/efi-loader.img")},format=raw]
+  ovmf = "OVMF.fd"
+  if File.exist?("/usr/share/edk2/x64/OVMF.fd")
+    ovmf = "/usr/share/edk2/x64/OVMF.fd"
+  elsif File.exist?("/usr/share/edk2/x64/OVMF.4m.fd")
+    ovmf = "/usr/share/edk2/x64/OVMF.4m.fd"
+  end
+	sh %W[qemu-system-x86_64 -bios #{ovmf} -drive file=#{uefi_env.expand("^/efi-loader.img")},format=raw]
 end