Download the Native Client SDK

To build Native Client modules, you must download and install the Native Client Software Development Kit (SDK). This page provides an overview of the Native Client SDK, and instructions for how to download and install the SDK.

Overview

The Native Client SDK includes the following:

support for multiple Pepper versions: The SDK contains bundles that let you compile Native Client modules using different versions of the Pepper Plugin API (e.g., Pepper 31 or Pepper Canary). Review the Release Notes for a description of the new features included in each Pepper version to help you decide which bundle to use to develop your application. In general, Native Client modules compiled using a particular Pepper version will work in corresponding versions of Chrome and higher. For example, a module compiled using the Pepper 31 bundle will work in Chrome 31 and higher.
update utility: The naclsdk utility (naclsdk.bat on Windows) lets you download new bundles that are available, as well as new versions of existing bundles.
toolchains: Each platform includes three toolchains: one for compiling Portable Native Client (PNaCl) applications, one for compiling architecture-specific Native Client applications with newlib, and one for compiling architecture-specific Native Client applications with glibc. Newlib and glibc are two different implementations of the C standard library. All three toolchains contain Native Client-compatible versions of standard compilers, linkers, and other tools. See NaCl and PNaCl to help you choose the right toolchain.
examples: Each example in the SDK includes C or C++ source files and header files illustrating how to use NaCl and Pepper, along with a Makefile to build the example using each of the toolchains.
tools: The SDK includes a number of additional tools that you can use for tasks such as validating Native Client modules and running modules from the command line.

Follow the steps below to download and install the Native Client SDK.

Prerequisites

Python: Make sure you have Python 2.6 or 2.7 installed, and that the Python executable is in your path.
- On Mac/Linux, Python is likely preinstalled. Run the command "python -V” in a terminal window, and make sure that the version of Python you have is 2.6.x or 2.7.x (if it’s not, upgrade to one of those versions).
- On Windows, you may need to install Python. Go to http://www.python.org/download/ and select the latest 2.x version. In addition, be sure to add the Python directory (for example, C:\python27) to the PATH environment variable. After you’ve installed Python, run the command "python -V” in a Command Prompt window and verify that the version of Python you have is 2.6.x or 2.7.x.
- Note that Python 3.x is not yet supported.
Make: On the Mac, you need to install the make command on your system before you can build and run the examples in the SDK. One easy way to get make, along with several other useful tools, is to install Xcode Developer Tools. After installing Xcode, go to the Preferences menu, select Downloads and Components, and verify that Command Line Tools are installed. If you’d rather not install Xcode, you can download and build an open source version of make. In order to build the command you may also need to download and install a copy of gcc.

Download and install the SDK

Download the SDK update utility: nacl_sdk.zip.
Unzip the SDK update utility:
- On Mac/Linux, run the command “unzip nacl_sdk.zip” in a terminal window.
- On Windows, right-click on the .zip file and select “Extract All...”. A dialog box will open; enter a location and click “Extract”.
Unzipping the SDK update utility creates a directory called nacl_sdk with the following files and directories:
- naclsdk (and naclsdk.bat for Windows) — the front end of the update utility, i.e., the command you run to download the latest bundles
- sdk_cache — a directory with a manifest file that lists the bundles you have already downloaded
- sdk_tools — the back end of the update utility, also known as the “sdk_tools” bundle
To see the SDK bundles that are available for download, go to the nacl_sdk directory and run naclsdk with the "list" command. The SDK includes a separate bundle for each version of Chrome/Pepper.

On Mac/Linux:
```
$ cd nacl_sdk
$ ./naclsdk list
```
On Windows:
```
> cd nacl_sdk
> naclsdk list
```
You should see output similar to this:
```
Bundles:
 I: installed
 *: update available

  I  sdk_tools (stable)
     vs_addin (dev)
     pepper_27 (post_stable)
     pepper_28 (post_stable)
     pepper_29 (post_stable)
     pepper_30 (post_stable)
     pepper_31 (stable)
     pepper_32 (beta)
     pepper_canary (canary)
```
The sample output above shows that there are a number of bundles available for download, and that you have already installed the latest revision of the sdk_tools bundle (it was included in the zip file you downloaded). Each bundle is labeled post-stable, stable, beta, dev, or canary. These labels usually correspond to the current versions of Chrome. (In the example above, Chrome 31 is stable, Chrome 32 is beta, etc.). We generally recommend that you download and use a “stable” bundle, as applications developed with “stable” bundles can be used by all current Chrome users. This is because Native Client is designed to be backward-compatible (for example, applications developed with the pepper_31 bundle can run in Chrome 31, Chrome 32, etc.). Thus in the example above, pepper_31 is the recommended bundle to use.
Run naclsdk with the “update” command to download recommended bundles.

On Mac/Linux:
```
$ ./naclsdk update
```
On Windows:
```
> naclsdk update
```
By default, naclsdk only downloads bundles that are recommended—generally those that are “stable.” Continuing with the earlier example, the “update” command would only download the pepper_31 bundle, since the bundles pepper_32 and greater are not yet stable. If you want the pepper_32 bundle, you must ask for it explicitly:
```
$ ./naclsdk update pepper_32
```
Note that you never need to update the sdk_tools bundle—it is updated automatically (if necessary) whenever you run naclsdk.

The minimum SDK bundle that supports PNaCl is pepper_31.

Staying up-to-date and getting new versions of bundles

Run naclsdk with the “list” command again; this will show you the list of available bundles and verify which bundles you have installed.

On Mac/Linux:

$ ./naclsdk list

On Windows:

> naclsdk list

Continuing with the earlier example, if you previously downloaded the pepper_31 bundle, you should see output similar to this:

Bundles:
 I: installed
 *: update available

  I  sdk_tools (stable)
     vs_addin (dev)
     pepper_27 (post_stable)
     pepper_28 (post_stable)
     pepper_29 (post_stable)
     pepper_30 (post_stable)
  I  pepper_31 (stable)
     pepper_32 (beta)
     pepper_canary (canary)

Running naclsdk with the “update” command again will verify that your bundles are up-to-date, or warn if you there are new versions of previously installed bundles.

On Mac/Linux:
```
$ ./naclsdk update
```
On Windows:
```
> naclsdk update
```
Continuing with the earlier example, you should see output similar to this:
```
pepper_31 is already up-to-date.
```

To check if there is a new version of a previously installed bundle, you can run the “list” command again:

Bundles:
 I: installed
 *: update available

  I  sdk_tools (stable)
     vs_addin (dev)
     pepper_27 (post_stable)
     pepper_28 (post_stable)
     pepper_29 (post_stable)
     pepper_30 (post_stable)
  I* pepper_31 (stable)
     pepper_32 (beta)
     pepper_canary (canary)

An asterisk next to a bundle indicates that there is an update available for that bundle. If you run the “update” command now, naclsdk will warn you with a message similar to this:

WARNING: pepper_31 already exists, but has an update available.
Run update with the --force option to overwrite the existing directory.
Warning: This will overwrite any modifications you have made within this directory.

To dowload the new version of a bundle and overwrite the existing directory for that bundle, run naclsdk with the --force option.

On Mac/Linux:

$ ./naclsdk update --force

On Windows:

> naclsdk update --force

For more information about the naclsdk utility, run:

On Mac/Linux:
```
$ ./naclsdk help
```
On Windows:
```
> naclsdk help
```

Next steps:

Browse through the Release Notes for important information about the SDK and new bundles.
If you’re just getting started with Native Client, we recommend reading the Technical Overview and walking through the Getting Started Tutorial.
If you’d rather dive into information about the toolchains, see Building Native Client Modules.