Index: clang/www/cxx_status.html
===================================================================
--- clang/www/cxx_status.html
+++ clang/www/cxx_status.html
@@ -1199,7 +1199,7 @@
     <tr>
       <td>Coroutines</td>
       <td><a href="https://wg21.link/p0912r5">P0912R5</a></td>
-      <td class="partial" align="center">Partial</td>
+      <td class="partial" align="center">Partial <a href="#CoroPartialReason">(12)</a></td>
     </tr>
     <!-- Cologne 2019 papers -->
     <tr>
@@ -1263,6 +1263,12 @@
 <tt>-std=c++20</tt>, but can be enabled with <tt>-fchar8_t</tt>.
 </span>
 </p>
+<p>
+<span id="CoroPartialReason">(12): The optimizer couldn't handle TLS with
+  `__attribute__((const))` attribute correctly. It implies that there would
+  be problems if the coroutine is possible to resume on a different thread.
+</span>
+</p>
 </details>
 
 <h2 id="cxx23">C++2b implementation status</h2>