server: Delay setting system registers until suspending select is waken.

server/thread.c

@@ -1706,7 +1706,13 @@ DECL_HANDLER(select)
     else if (get_error() != STATUS_PENDING && get_reply_max_size() == sizeof(context_t) &&
              current->context && current->suspend_cookie == req->cookie)
     {
-        if (current->context->regs.flags) set_reply_data( &current->context->regs, sizeof(context_t) );
+        if (current->context->regs.flags)
+        {
+            unsigned int system_flags = get_context_system_regs(current->process->cpu) &
+                                        current->context->regs.flags;
+            if (system_flags) set_thread_context( current, &current->context->regs, system_flags );
+            set_reply_data( &current->context->regs, sizeof(context_t) );
+        }
         release_object( current->context );
         current->context = NULL;
     }
@@ -1896,14 +1902,13 @@ DECL_HANDLER(set_thread_context)
     else
     {
         unsigned int system_flags = get_context_system_regs(context->cpu) & context->flags;
-        unsigned int client_flags = context->flags & ~system_flags;
 
-        if (system_flags) set_thread_context( thread, context, system_flags );
-        if (thread != current && !get_error()) stop_thread( thread );
+        if (thread != current) stop_thread( thread );
+        else if (system_flags) set_thread_context( thread, context, system_flags );
         if (thread->context && !get_error())
         {
             copy_context( &thread->context->regs, context, context->flags );
-            thread->context->regs.flags |= client_flags;
+            thread->context->regs.flags |= context->flags;
         }
     }