Index: include/lldb/Core/DataBufferMemoryMap.h
===================================================================
--- include/lldb/Core/DataBufferMemoryMap.h
+++ include/lldb/Core/DataBufferMemoryMap.h
@@ -100,7 +100,12 @@
     /// @param[in] length
     ///     The size in bytes that should be mapped starting \a offset
     ///     bytes into the file. If \a length is \c SIZE_MAX, map
-    ///     as many bytes as possible.
+    ///     as many bytes as possible.  Even though it may be possible
+    ///     for a 32-bit host debugger to debug a 64-bit target, size_t
+    ///     still dictates the maximum possible size that can be mapped
+    ///     into this process.  For this kind of cross-arch debugging
+    ///     scenario, mappings and views should be managed at a higher
+    ///     level.
     ///
     /// @return
     ///     The number of bytes mapped starting from the \a offset.