Native Client

Running the SDK Examples

Every Native Client SDK bundle comes with a folder of example applications. Each example demonstrates one or two key Native Client programming concepts. After you’ve downloaded the SDK, follow the instructions on this page to build and run the examples.

Configure the Google Chrome Browser

  1. Your version of Chrome must be equal to or greater than the version of your SDK bundle. For example, if you’re developing with the pepper_31 bundle, you must use Google Chrome version 31 or greater. To find out what version of Chrome you’re using, type about:chrome or about:version in the Chrome address bar.

  2. For Portable Native Client, no extra Chrome flags are needed as of Chrome version 31.

    For other Native Client applications, or to debug Portable Native Client applications by translating the pexe to a nexe ahead of time, enable the Native Client flag. Native Client is enabled by default only for applications distributed through the Chrome Web Store. To run Native Client applications that are not distributed through the Chrome Web Store, like the SDK examples, you must specifically enable the Native Client flag in Chrome:

    • Type about:flags in the Chrome address bar and scroll down to “Native Client”.

    • If the link below “Native Client” says “Disable”, then Native Client is already enabled and you don’t need to do anything else.

    • If the link below “Native Client” says “Enable”, click the “Enable” link, scroll down to the bottom of the page, and click the “Relaunch Now” button. All browser windows will restart when you relaunch Chrome.

  3. Disable the Chrome cache. Chrome caches resources aggressively; when you are building a Native Client application you should disable the cache to make sure that Chrome loads the latest version:

    • Open Chrome’s developer tools by clicking the menu icon menu-icon and choosing Tools > Developer tools.

    • Click the gear icon gear-icon in the bottom right corner of the Chrome window.

    • Under the “General” settings, check the box next to “Disable cache”.

Build the SDK examples

Starting with the pepper_24 bundle, the Makefile scripts for the SDK examples build multiple versions of the examples using all three SDK toolchains (newlib, glibc, and PNaCl) and in both release and debug configurations. (Note that some examples build only with the particular toolchains).

To build all the examples, go to the examples directory in a specific SDK bundle and run make:

$ cd pepper_31/examples
$ make
make -C api  all
make[1]: Entering directory `pepper_31/examples/api'
make -C audio  all
make[2]: Entering directory `pepper_31/examples/api/audio'
  CXX  newlib/Debug/audio_x86_32.o
  LINK newlib/Debug/audio_x86_32.nexe
  CXX  newlib/Debug/audio_x86_64.o
  LINK newlib/Debug/audio_x86_64.nexe
  CXX  newlib/Debug/audio_arm.o
  LINK newlib/Debug/audio_arm.nexe
  CREATE_NMF newlib/Debug/audio.nmf
make[2]: Leaving directory `pepper_31/examples/api/audio'
make -C url_loader  all
make[2]: Entering directory `pepper_31/examples/api/url_loader'
  CXX  newlib/Debug/url_loader_x86_32.o

Calling make from inside a particular example’s directory will build only that example:

$ cd pepper_31/examples/api/core
$ make
  CXX  newlib/Debug/core_x86_32.o
  LINK newlib/Debug/core_x86_32.nexe
  CXX  newlib/Debug/core_x86_64.o
  LINK newlib/Debug/core_x86_64.nexe
  CXX  newlib/Debug/core_arm.o
  LINK newlib/Debug/core_arm.nexe
  CREATE_NMF newlib/Debug/core.nmf

You can call make with the TOOLCHAIN and CONFIG parameters to override the defaults:

$ make TOOLCHAIN=pnacl CONFIG=Release
  CXX  pnacl/Release/core_pnacl.o
  LINK pnacl/Release/core.bc
  FINALIZE pnacl/Release/core.pexe
  CREATE_NMF pnacl/Release/core.nmf

You can also set TOOLCHAIN to “all” to build one or more examples with all available toolchains:

$ make TOOLCHAIN=all
make TOOLCHAIN=newlib
make[1]: Entering directory `pepper_31/examples/api/core'
  CXX  newlib/Debug/core_x86_32.o
  LINK newlib/Debug/core_x86_32.nexe
  CXX  newlib/Debug/core_x86_64.o
  LINK newlib/Debug/core_x86_64.nexe
  CXX  newlib/Debug/core_arm.o
  LINK newlib/Debug/core_arm.nexe
  CREATE_NMF newlib/Debug/core.nmf
make[1]: Leaving directory `pepper_31/examples/api/core'
make TOOLCHAIN=glibc
make[1]: Entering directory `pepper_31/examples/api/core'
  CXX  glibc/Debug/core_x86_32.o
  LINK glibc/Debug/core_x86_32.nexe
  CXX  glibc/Debug/core_x86_64.o
  LINK glibc/Debug/core_x86_64.nexe
  CREATE_NMF glibc/Debug/core.nmf
make[1]: Leaving directory `pepper_31/examples/api/core'
make TOOLCHAIN=pnacl
make[1]: Entering directory `pepper_31/examples/api/core'
  CXX  pnacl/Debug/core_pnacl.o
  LINK pnacl/Debug/core.bc
  FINALIZE pnacl/Debug/core.pexe
  TRANSLATE pnacl/Debug/core_x86_32.nexe
  TRANSLATE pnacl/Debug/core_x86_64.nexe
  TRANSLATE pnacl/Debug/core_arm.nexe
  CREATE_NMF pnacl/Debug/core.nmf
make[1]: Leaving directory `pepper_31/examples/api/core'
make TOOLCHAIN=linux
make[1]: Entering directory `pepper_31/examples/api/core'
  CXX  linux/Debug/core.o
  LINK linux/Debug/
make[1]: Leaving directory `pepper_31/examples/api/core'

After running make, each example directory will contain one or more of the following subdirectories:

  • a newlib directory with subdirectories Debug and Release;
  • a glibc directory with subdirectories Debug and Release;
  • a pnacl directory with subdirectories Debug and Release;

For the newlib and glibc toolchains the Debug and Release subdirectories contain .nexe files for all target architectures. For the PNaCl toolchain they contain a single .pexe file. PNaCl debug also produces pre-translated .nexe files, for ease of debugging. All Debug and Release directories contain a manifest (.nmf) file that references the associated .nexe or .pexe files. For information about Native Client manifest files, see the Technical Overview.

For details on how to use make, see the GNU ‘make’ Manual. For details on how to use the SDK toolchain itself, see Building Native Client Modules.

Run the SDK examples

To run the SDK examples, you can use the make run command:

$ cd pepper_31/examples/api/core
$ make run

This will launch a local HTTP server which will serve the data for the example. It then launches Chrome with the address of this server, usually http://localhost:5103. After you close Chrome, the local HTTP server is automatically shutdown.

This command will try to find an executable named google-chrome in your PATH environment variable. If it can’t, you’ll get an error message like this:

pepper_31/tools/ No valid Chrome found at CHROME_PATH=
pepper_31/tools/ *** Set CHROME_PATH via an environment variable, or command-line..  Stop.

Set the CHROME_PATH environment variable to the location of your Chrome executable.

On Windows:

> set CHROME_PATH=<Path to chrome.exe>

On Linux:

$ export CHROME_PATH=<Path to google-chrome>

On Mac:

$ export CHROME_PATH=<Path to chrome>

You can run via a different toolchain or configuration by using the TOOLCHAIN and CONFIG parameters to make:

$ make run TOOLCHAIN=pnacl CONFIG=Debug

Run the SDK examples as packaged apps

Each example can also be launched as a packaged app. For more information about using Native Client for packaged apps, see Packaged appliction. For general information about packaged apps, see the Chrome apps documentation.

Some Pepper features, such as TCP/UDP socket access, are only allowed in packaged apps. The examples that use these features must be run as packaged apps, by using the make run_package command:

$ make run_package

You can use TOOLCHAIN and CONFIG parameters as above to run with a different toolchain or configuration.

Debugging the SDK examples

The NaCl SDK uses GDB to debug Native Client code. The SDK includes a prebuilt version of GDB that is compatible with NaCl code. To use it, run the make debug command from an example directory:

$ make debug

This will launch Chrome with the --enable-nacl-debug flag set. This flag will cause Chrome to pause when a NaCl module is first loaded, waiting for a connection from gdb. The make debug command also simultaneously launches GDB and loads the symbols for that NEXE. To connect GDB to Chrome, in the GDB console, type:

(gdb) target remote :4014

This tells GDB to connect to a TCP port on localhost:4014–the port that Chrome is listening on. GDB will respond:

Remote debugging using :4014
0x000000000fa00080 in ?? ()

At this point, you can use the standard GDB commands to debug your NaCl module. The most common commands you will use to debug are continue, step, next, break and backtrace. See Debugging for more information about debugging a Native Client application.

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