Index: native_client_sdk/src/doc/nacl-and-pnacl.rst |
diff --git a/native_client_sdk/src/doc/nacl-and-pnacl.rst b/native_client_sdk/src/doc/nacl-and-pnacl.rst |
index 2a0872b2b982af7ccf3b90e93bbfa5f8f4b5c656..7e9c2942016c9e1ead0066d86f3627d743f265e5 100644 |
--- a/native_client_sdk/src/doc/nacl-and-pnacl.rst |
+++ b/native_client_sdk/src/doc/nacl-and-pnacl.rst |
@@ -24,8 +24,8 @@ web technologies, by running compiled C and C++ code at near-native speeds and |
taking advantage of multiple cores with shared memory. |
While Native Client provides operating system independence, it requires |
-developers to generate architecture-specific executable modules |
-(**nexe** modules) for each hardware platform. This is not only inconvenient |
+developers to generate architecture-specific executable |
+(**nexe**) modules for each hardware platform. This is not only inconvenient |
for developers, but architecture-specific machine code is not portable and thus |
not well-suited for the open web. The traditional method of application |
distribution on the web is through a self-contained bundle of HTML, CSS, |
@@ -44,15 +44,14 @@ PNaCl solves the portability problem by splitting the compilation process |
into two parts: |
#. compiling the source code to a portable bitcode format, and |
-#. translating the bitcode to a host-specific executable. |
+#. translating the bitcode to a host-specific executable just before execution. |
-PNaCl enables developers |
-to distribute **portable executables** (**pexe** modules) that the hosting |
-environment (e.g., the Chrome browser) can translate to native code before |
-executing. This portability aligns Native Client with existing open web |
-technologies such as JavaScript: A developer can distribute a **pexe** |
-as part of an application (along with HTML, CSS, and JavaScript), |
-and the user's machine is simply able to run it. |
+PNaCl enables developers to distribute **portable executables** (**pexe**) |
+modules that the hosting environment (in other words, the Chrome browser) can |
+translate to native code before executing. This portability aligns Native Client |
+with existing open web technologies such as JavaScript. A developer can |
+distribute a **pexe** as part of an application (along with HTML, CSS, and |
+JavaScript), and the user's machine is simply able to run it. |
With PNaCl, a developer generates a single **pexe** from source code, |
rather than multiple platform-specific nexes. The **pexe** provides both |
@@ -61,17 +60,12 @@ architecture-independent format, it does not suffer from the portability |
problem described above. Future versions of hosting environments should |
have no problem executing the **pexe**, even on new architectures. |
Moreover, if an existing architecture is subsequently enhanced, the |
-**pexe** doesn't even have to be recompiled---in some cases the |
+**pexe** doesn't even have to be recompiled. In some cases the |
client-side translation will automatically be able to take advantage of |
-the new capabilities. |
- |
-**In short, PNaCl combines the portability of existing web technologies with |
-the performance and security benefits of Native Client.** |
- |
-With the advent of PNaCl, the distribution restriction of Native Client |
-can be lifted. Specifically, a **pexe** module can be part of any web |
-application---it does not have to be distributed through the Chrome Web |
-Store. |
+the new capabilities. A **pexe** module can be part of any web |
+application. It does not have to be distributed through the Chrome Web |
+Store. In short, PNaCl combines the portability of existing web technologies |
+with the performance and security benefits of Native Client. |
PNaCl is a new technology, and as such it still has a few limitations |
as compared to NaCl. These limitations are described below. |
@@ -107,14 +101,14 @@ The limitations below apply to the current release of PNaCl. If any of |
these limitations are critical for your application, you should use |
non-portable NaCl: |
-* By its nature, PNaCl does not support architecture-specific |
+* PNaCl does not support architecture-specific |
instructions in an application (i.e., inline assembly), but tries to |
offer high-performance portable equivalents. One such example is |
PNaCl's :ref:`Portable SIMD Vectors <portable_simd_vectors>`. |
-* Currently PNaCl only supports static linking with the ``newlib`` |
+* PNaCl only supports static linking with the ``newlib`` |
C standard library (the Native Client SDK provides a PNaCl port of |
``newlib``). Dynamic linking and ``glibc`` are not yet supported. |
Work is under way to enable dynamic linking in future versions of PNaCl. |
-* In the initial release, PNaCl does not support some GNU extensions |
+* PNaCl does not support some GNU extensions |
like taking the address of a label for computed ``goto``, or nested |
functions. |