NaCl docs: mention static libraries for SJLJ

native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst

Index: native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
diff --git a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
index 2324774fa8c20b4d393bc058155489d823d9f034..117d9314c9a00c6d036dd01d207c9af39bff4981 100644
--- a/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
+++ b/native_client_sdk/src/doc/reference/pnacl-c-cpp-language-support.rst
@@ -176,12 +176,20 @@ C++ Exception Handling
 ======================
 
 PNaCl currently supports C++ exception handling through ``setjmp()`` and
-``longjmp()``, which can be enabled with the ``--pnacl-exceptions=sjlj``
-linker flag. Exceptions are disabled by default so that faster and
-smaller code is generated, and ``throw`` statements are replaced with
-calls to ``abort()``. The usual ``-fno-exceptions`` flag is also
-supported. PNaCl will support full zero-cost exception handling in the
-future.
+``longjmp()``, which can be enabled with the ``--pnacl-exceptions=sjlj`` linker
+flag (set with ``LDFLAGS`` when using Make). Exceptions are disabled by default

[Sam Clegg, 2015/02/19 18:37:47]

Is it a linker flag?  I assumed it was a compiler flag.  If its a linker flag
there is no need to rebuild the libraries (maybe for glibc which uses shared
libraries).

[JF, 2015/02/19 19:15:45]

That's entirely true! Docs updated, thanks for catching this.

+so that faster and smaller code is generated, and ``throw`` statements are
+replaced with calls to ``abort()``. The usual ``-fno-exceptions`` flag is also
+supported, though the default is ``-fexceptions``. PNaCl will support full
+zero-cost exception handling in the future.
+
+.. note:: When using naclports_ or other prebuilt static libraries, you'll want
+          to make sure these libraries are built with the same configuration
+          your library is built with. If you want to use exception handling,
+          then you'll need to rebuild these libraries with exception handling
+          enabled. For naclports, you'll want to modify the port's ``build.sh``.
+
+.. _naclports: https://code.google.com/p/naclports
 
 NaCl supports full zero-cost C++ exception handling.