Update InteropServices doc

xml/System.Runtime.InteropServices.ObjectiveC/ObjectiveCMarshal+UnhandledExceptionPropagationHandler.xml

@@ -25,7 +25,7 @@
     <param name="lastMethod">Last managed method.</param>
     <param name="context">Context provided to the returned function pointer.</param>
     <summary>Handler for unhandled Exceptions crossing the managed -&gt; native boundary (that is, Reverse P/Invoke).</summary>
-    <returns>To be added.</returns>
+    <returns>Exception propagation callback.</returns>
     <remarks>
       <format type="text/markdown"><![CDATA[
 

xml/System.Runtime.InteropServices.ObjectiveC/ObjectiveCMarshal.xml

@@ -102,12 +102,23 @@ The Initialize() must be called prior to calling this function.
         <Parameter Name="unhandledExceptionPropagationHandler" Type="System.Runtime.InteropServices.ObjectiveC.ObjectiveCMarshal+UnhandledExceptionPropagationHandler" />
       </Parameters>
       <Docs>
-        <param name="beginEndCallback">To be added.</param>
-        <param name="isReferencedCallback">To be added.</param>
-        <param name="trackedObjectEnteredFinalization">To be added.</param>
-        <param name="unhandledExceptionPropagationHandler">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="beginEndCallback">Called when tracking begins and ends.</param>
+        <param name="isReferencedCallback">Called to determine if a managed object instance is referenced elsewhere, and must not be collected by the GC.</param>
+        <param name="trackedObjectEnteredFinalization">Called when a tracked object enters the finalization queue.</param>
+        <param name="unhandledExceptionPropagationHandler">Handler for the propagation of unhandled Exceptions across a managed -&gt; native boundary (that is, Reverse P/Invoke).</param>
+        <summary>Initialize the Objective-C marshalling API.</summary>
+        <remarks>
+All unmanaged function pointers must be written in native code since they will be called by the GC and
+managed code is not able to run at that time.
+
+The <paramref name="beginEndCallback"/> will be called when reference tracking begins and ends.
+The associated begin/end pair will never be nested. When using Workstation GC, the begin/end pair
+will be called on the same thread. When using Server GC, the begin/end pair is not guaranteed to
+be called on the same thread.
+
+The <paramref name="isReferencedCallback"/> should return 0 for not reference or 1 for
+referenced. Any other value has undefined behavior.
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="SetMessageSendCallback">

xml/System.Runtime.InteropServices/Architecture.xml

@@ -142,7 +142,7 @@
       </ReturnValue>
       <MemberValue>5</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>The S390x platform architecture.</summary>
       </Docs>
     </Member>
     <Member MemberName="Wasm">

xml/System.Runtime.InteropServices/CollectionsMarshal.xml

@@ -75,8 +75,8 @@
         <Parameter Name="exists" Type="System.Boolean" RefType="out" Index="2" FrameworkAlternate="net-6.0" />
       </Parameters>
       <Docs>
-        <typeparam name="TKey">To be added.</typeparam>
-        <typeparam name="TValue">To be added.</typeparam>
+        <typeparam name="TKey">The type of a key.</typeparam>
+        <typeparam name="TValue">The type of a value.</typeparam>
         <param name="dictionary">The dictionary to get the reference to <typeparamref name="TValue" /> from.</param>
         <param name="key">The key used for lookup.</param>
         <param name="exists">When this method returns, contains <see langword="true" /> if <paramref name="key" /> already existed in the dictionary, and <see langword="false" /> if a new entry was added.</param>
@@ -117,8 +117,8 @@ Items should not be added to or removed from the <xref:System.Collections.Generi
         <Parameter Name="key" Type="TKey" Index="1" FrameworkAlternate="net-6.0" />
       </Parameters>
       <Docs>
-        <typeparam name="TKey">To be added.</typeparam>
-        <typeparam name="TValue">To be added.</typeparam>
+        <typeparam name="TKey">The type of a key.</typeparam>
+        <typeparam name="TValue">The type of a value.</typeparam>
         <param name="dictionary">The dictionary to get the ref to <typeparamref name="TValue" /> from.</param>
         <param name="key">The key used for lookup.</param>
         <summary>Gets either a ref to a <typeparamref name="TValue" /> in the <see cref="T:System.Collections.Generic.Dictionary`2" /> or a ref <see langword="null" /> if it does not exist in the <paramref name="dictionary" />.</summary>

xml/System.Runtime.InteropServices/MemoryMarshal.xml

@@ -682,7 +682,7 @@ This method can be useful if part of a managed object represents a fixed array.
         <Parameter Name="array" Type="System.Array" Index="0" FrameworkAlternate="net-6.0" />
       </Parameters>
       <Docs>
-        <param name="array">To be added.</param>
+        <param name="array">The array to analyze.</param>
         <summary>Returns a reference to the 0th element of <paramref name="array" />. If the array is empty, returns a reference to where the 0th element would have been stored. Such a reference may be used for pinning but must never be dereferenced.</summary>
         <returns>To be added.</returns>
         <remarks>

xml/System.Runtime.InteropServices/PosixSignalContext.xml

@@ -34,7 +34,7 @@
         <Parameter Name="signal" Type="System.Runtime.InteropServices.PosixSignal" />
       </Parameters>
       <Docs>
-        <param name="signal">To be added.</param>
+        <param name="signal">The signal that occurred.</param>
         <summary>Initializes a new instance of the <see cref="T:System.Runtime.InteropServices.PosixSignalContext" /> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>

xml/System.Runtime.InteropServices/UnmanagedCallConvAttribute.xml

@@ -37,7 +37,7 @@
       </AssemblyInfo>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Initializes a new <see cref="T:System.Runtime.InteropServices.UnmanagedCallConvAttribute" /> instance.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/ns-System.Runtime.InteropServices.ObjectiveC.xml

@@ -1,6 +1,6 @@
 <Namespace Name="System.Runtime.InteropServices.ObjectiveC">
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Contains classes that support interoperation between managed code and the Objective-C Runtime.</summary>
     <remarks>To be added.</remarks>
   </Docs>
 </Namespace>