Add documentation warning for Interlocked.Read write access requirement on 32-bit platforms (#11659)

Fixes #11658

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: jkotas <[email protected]>

Author: Copilot

xml/System.Threading/Interlocked.xml

@@ -2950,6 +2950,9 @@ This method wraps a call to [FlushProcessWriteBuffers](/windows/win32/api/proces
 ## Remarks
  The <xref:System.Threading.Interlocked.Read%2A> method is unnecessary on 64-bit systems, because 64-bit read operations are already atomic. On 32-bit systems, 64-bit read operations are not atomic unless performed using <xref:System.Threading.Interlocked.Read%2A>.
 
+> [!IMPORTANT]
+> On 32-bit platforms, despite taking a readonly reference parameter, this method requires write access to the memory location because it uses <xref:System.Threading.Interlocked.CompareExchange%2A> internally to ensure atomicity. Attempting to read from read-only memory (such as memory-mapped files opened with read-only access) can result in an <xref:System.AccessViolationException>.
+
  ]]></format>
         </remarks>
         <altmember cref="Overload:System.Threading.Interlocked.Increment" />
@@ -3006,7 +3009,17 @@ This method wraps a call to [FlushProcessWriteBuffers](/windows/win32/api/proces
         <param name="location">The 64-bit value to be loaded.</param>
         <summary>Returns a 64-bit unsigned value, loaded as an atomic operation.</summary>
         <returns>The loaded value.</returns>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+ The <xref:System.Threading.Interlocked.Read%2A> method is unnecessary on 64-bit systems, because 64-bit read operations are already atomic. On 32-bit systems, 64-bit read operations are not atomic unless performed using <xref:System.Threading.Interlocked.Read%2A>.
+
+> [!IMPORTANT]
+> On 32-bit platforms, despite taking a readonly reference parameter, this method requires write access to the memory location because it uses <xref:System.Threading.Interlocked.CompareExchange%2A> internally to ensure atomicity. Attempting to read from read-only memory (such as memory-mapped files opened with read-only access) can result in an <xref:System.AccessViolationException>.
+
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="SpeculationBarrier">