Default _OSI can be passed a string reference

src/aml/namespace.rs

@@ -69,7 +69,7 @@ impl Namespace {
                     if args.len() != 1 {
                         return Err(AmlError::MethodArgCountIncorrect);
                     }
-                    let Object::String(ref feature) = *args[0] else {
+                    let Object::String(ref feature) = *args[0].clone().unwrap_reference() else {
                         return Err(AmlError::ObjectNotOfExpectedType {
                             expected: ObjectType::String,
                             got: args[0].typ(),

tests/osi.asl

@@ -0,0 +1,60 @@
+// Check a variety of _OSI parameters and formats. These are a fairly random selection.
+//
+// Most of these call _OSI by reference, but also check that a native string works
+//
+// Adapted from the uACPI test of the same name.
+DefinitionBlock ("", "DSDT", 2, "RSCAPI", "OSI", 0xF0F0F0F0)
+{
+    Method (CHEK, 2) {
+        Local0 = _OSI(Arg0)
+
+        If (Local0 != Arg1) {
+            Printf("_OSI(%o) failed (expected %o, got %o)", Arg0, Arg1, Local0)
+            Return (1)
+        }
+
+        Return (0)
+    }
+
+    Method (MAIN, 0, NotSerialized)
+    {
+        Local0 = 0
+
+        If (!CondRefOf(_OSI)) {
+            Debug = "No _OSI method!"
+            Return (1111111)
+        }
+
+        if (_OSI("Windows 2000") != Ones) {
+            Local0 += 1
+        }
+
+        Local0 += CHEK("Windows 2000", Ones)
+        Local0 += CHEK("Windows 2001", Ones)
+        Local0 += CHEK("Windows 2001 SP1", Ones)
+        Local0 += CHEK("Windows 2001.1", Ones)
+        Local0 += CHEK("Windows 2001 SP2", Ones)
+        Local0 += CHEK("Windows 2001.1 SP1", Ones)
+        Local0 += CHEK("Windows 2006.1", Ones)
+        Local0 += CHEK("Windows 2006 SP1", Ones)
+        Local0 += CHEK("Windows 2006 SP2", Ones)
+        Local0 += CHEK("Windows 2009", Ones)
+        Local0 += CHEK("Windows 2012", Ones)
+        Local0 += CHEK("Windows 2013", Ones)
+        Local0 += CHEK("Windows 2015", Ones)
+        Local0 += CHEK("Windows 2016", Ones)
+        Local0 += CHEK("Windows 2017", Ones)
+        Local0 += CHEK("Windows 2017.2", Ones)
+        Local0 += CHEK("Windows 2018", Ones)
+        Local0 += CHEK("Windows 2018.2", Ones)
+        Local0 += CHEK("Windows 2019", Ones)
+
+        Local0 += CHEK("Processor Device", Zero)
+        Local0 += CHEK("", Zero)
+        Local0 += CHEK("Windows 99999", Zero)
+        Local0 += CHEK("Windows 2014", Zero)
+        Local0 += CHEK("Linux", Zero)
+
+        Return (Local0)
+    }
+}