README.build - platform/external/libwebsockets - Git at Google

 Introduction to CMake
 ---------------------

 CMake is a multi-platform build tool that can generate build files for many
 different target platforms. See more info at http://www.cmake.org

 CMake also allows/recommends you to do "out of source"-builds, that is,
 the build files are separated from your sources, so there is no need to
 create elaborate clean scripts to get a clean source tree, instead you
 simply remove your build directory.

 Libwebsockets has been tested to build successfully on the following platforms
 with SSL support (both OpenSSL/CyaSSL):

 - Windows
 - Linux (x86 and ARM)
 - OSX
 - NetBSD

 Building the library and test apps
 ----------------------------------

 The project settings used by CMake to generate the platform specific build
 files is called CMakeLists.txt. CMake then uses one of its "Generators" to
 output a Visual Studio project or Make file for instance. To see a list of
 the available generators for your platform, simply run the "cmake" command.

 Note that by default OpenSSL will be linked, if you don't want SSL support
 see below on how to toggle compile options.

 Building on Unix:
 -----------------

 1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html
    (Most Unix distributions comes with a packaged version also)

 2. Install OpenSSL.

 3. Generate the build files (default is Make files):

 	cd /path/to/src
 	mkdir build
 	cd build
 	cmake ..

 	(NOTE: The build/ directory can have any name and be located anywhere
 	 on your filesystem, and that the argument ".." given to cmake is simply
 	 the source directory of libwebsockets containing the CMakeLists.txt
 	 project file. All examples in this file assumes you use "..")

 	NOTE2
 	A common option you may want to give is to set the install path, same
 	as --prefix= with autotools.  It defaults to /usr/local.
 	You can do this by, eg

 	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr

 	NOTE3
 	On machines that want libraries in lib64, you can also add the
 	following to the cmake line

 		-DLIB_SUFFIX=64

 4. Finally you can build using the generated Makefile:

 	make

 Building on Windows (Visual Studio)
 -----------------------------------
 1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html

 2. Install OpenSSL binaries. http://www.openssl.org/related/binaries.html
    (Preferably in the default location to make it easier for CMake to find them)

 3. Generate the Visual studio project by opening the Visual Studio cmd prompt:

    cd <path to src>
    md build
    cd build
    cmake -G "Visual Studio 10" ..

    (NOTE: There is also a cmake-gui available on Windows if you prefer that)

 4. Now you should have a generated Visual Studio Solution in  your
    <path to src>/build directory, which can be used to build.

 Setting compile options
 -----------------------

 To set compile time flags you can either use one of the CMake gui applications
 or do it via command line.

 Command line
 ------------
 To list avaialable options (ommit the H if you don't want the help text):

 	cmake -LH ..

 Then to set an option and build (for example turn off SSL support):

 	cmake -DWITH_SSL=0 ..
 or
 	cmake -DWITH_SSL:BOOL=OFF ..

 Unix GUI
 --------
 If you have a curses enabled build you simply type:
 (not all packages include this, my debian install does not for example).

 	ccmake

 Windows GUI
 -----------
 On windows CMake comes with a gui application:
 	Start -> Programs -> CMake -> CMake (cmake-gui)

 CyaSSL replacement for OpenSSL
 ------------------------------
 CyaSSL is a lightweight SSL library targeted at embedded system:
 http://www.yassl.com/yaSSL/Products-cyassl.html

 It contains a OpenSSL compatability layer which makes it possible to pretty
 much link to it instead of OpenSSL, giving a much smaller footprint.

 NOTE: At the time of writing this the current release of CyaSSL contains a
 crash bug due to some APIs libwebsocket uses. To be able to use this you will
 need to use the current HEAD in their official repository:
 	https://github.com/cyassl/cyassl

 NOTE: cyassl needs to be compiled using the --enable-opensslExtra flag for
 this to work.

 Compiling libwebsockets with CyaSSL
 -----------------------------------

 cmake -DUSE_CYASSL=1
 	  -DCYASSL_INCLUDE_DIRS=/path/to/cyassl
 	  -DCYASSL_LIB=/path/to/cyassl/cyassl.a ..

 NOTE: On windows use the .lib file extension for CYASSL_LIB instead.

 Cross compiling
 ---------------
 To enable cross compiling libwebsockets using CMake you need to create
 a "Toolchain file" that you supply to CMake when generating your build files.
 CMake will then use the cross compilers and build paths specified in this file
 to look for dependencies and such.

 Libwebsockets includes an example toolchain file cross-arm-linux-gnueabihf.cmake
 you can use as a starting point.

 The commandline to configure for cross with this would look like

 cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr \
 	 -DCMAKE_TOOLCHAIN_FILE=../cross-arm-linux-gnueabihf.cmake \
 	 -DWITHOUT_EXTENSIONS=1 -DWITH_SSL=0

 The example shows how to build with no external cross lib dependencies, you
 need to proide the cross libraries otherwise.

 NOTE: start from an EMPTY build directory if you had a non-cross build in there
 	before the settings will be cached and your changes ignored.

 Additional information on cross compilation with CMake:
 	http://www.vtk.org/Wiki/CMake_Cross_Compiling


 Memory efficiency
 -----------------

 Embedded server-only configuration without extensions (ie, no compression
 on websocket connections), but with full v13 websocket features and http
 server, built on ARM Cortex-A9:

 Update at 8dac94d (2013-02-18)

 ./configure --without-client --without-extensions --disable-debug --without-daemonize

 Context Creation, 1024 fd limit[2]:   16720 (includes 12 bytes per fd)
 Per-connection [3]:                      72 bytes, +1328 during headers

 .text	.rodata	.data	.bss
 11512	2784	288	4

 This shows the impact of the major configuration with/without options at
 13ba5bbc633ea962d46d using Ubuntu ARM on a PandaBoard ES.

 These are accounting for static allocations from the library elf, there are
 additional dynamic allocations via malloc.  These are a bit old now but give
 the right idea for relative "expense" of features.

 Static allocations, ARM9
 				.text	.rodata	.data	.bss
  All (no without)		35024	9940	336	4104
  without client			25684	7144	336	4104
  without client, exts		21652	6288	288	4104
  without client, exts, debug[1]	19756	3768	288	4104
  without server			30304	8160	336	4104
  without server, exts		25382	7204	288	4104
  without server, exts, debug[1]	23712	4256	288	4104

 [1] --disable-debug only removes messages below lwsl_notice.  Since that is
 the default logging level the impact is not noticable, error, warn and notice
 logs are all still there.

 [2] 1024 fd per process is the default limit (set by ulimit) in at least Fedora
 and Ubuntu.  You can make significant savings tailoring this to actual expected
 peak fds, ie, at a limit of 20, context creation allocation reduces to 4432 +
 240 = 4672)

 [3] known header content is freed after connection establishment
	Introduction to CMake
	---------------------

	CMake is a multi-platform build tool that can generate build files for many
	different target platforms. See more info at http://www.cmake.org

	CMake also allows/recommends you to do "out of source"-builds, that is,
	the build files are separated from your sources, so there is no need to
	create elaborate clean scripts to get a clean source tree, instead you
	simply remove your build directory.

	Libwebsockets has been tested to build successfully on the following platforms
	with SSL support (both OpenSSL/CyaSSL):

	- Windows
	- Linux (x86 and ARM)
	- OSX
	- NetBSD

	Building the library and test apps
	----------------------------------

	The project settings used by CMake to generate the platform specific build
	files is called CMakeLists.txt. CMake then uses one of its "Generators" to
	output a Visual Studio project or Make file for instance. To see a list of
	the available generators for your platform, simply run the "cmake" command.

	Note that by default OpenSSL will be linked, if you don't want SSL support
	see below on how to toggle compile options.

	Building on Unix:
	-----------------

	1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html
	(Most Unix distributions comes with a packaged version also)

	2. Install OpenSSL.

	3. Generate the build files (default is Make files):

	cd /path/to/src
	mkdir build
	cd build
	cmake ..

	(NOTE: The build/ directory can have any name and be located anywhere
	on your filesystem, and that the argument ".." given to cmake is simply
	the source directory of libwebsockets containing the CMakeLists.txt
	project file. All examples in this file assumes you use "..")

	NOTE2
	A common option you may want to give is to set the install path, same
	as --prefix= with autotools. It defaults to /usr/local.
	You can do this by, eg

	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr

	NOTE3
	On machines that want libraries in lib64, you can also add the
	following to the cmake line

	-DLIB_SUFFIX=64

	4. Finally you can build using the generated Makefile:

	make

	Building on Windows (Visual Studio)
	-----------------------------------
	1. Install CMake 2.6 or greater: http://cmake.org/cmake/resources/software.html

	2. Install OpenSSL binaries. http://www.openssl.org/related/binaries.html
	(Preferably in the default location to make it easier for CMake to find them)

	3. Generate the Visual studio project by opening the Visual Studio cmd prompt:

	cd <path to src>
	md build
	cd build
	cmake -G "Visual Studio 10" ..

	(NOTE: There is also a cmake-gui available on Windows if you prefer that)

	4. Now you should have a generated Visual Studio Solution in your
	<path to src>/build directory, which can be used to build.

	Setting compile options
	-----------------------

	To set compile time flags you can either use one of the CMake gui applications
	or do it via command line.

	Command line
	------------
	To list avaialable options (ommit the H if you don't want the help text):

	cmake -LH ..

	Then to set an option and build (for example turn off SSL support):

	cmake -DWITH_SSL=0 ..
	or
	cmake -DWITH_SSL:BOOL=OFF ..

	Unix GUI
	--------
	If you have a curses enabled build you simply type:
	(not all packages include this, my debian install does not for example).

	ccmake

	Windows GUI
	-----------
	On windows CMake comes with a gui application:
	Start -> Programs -> CMake -> CMake (cmake-gui)

	CyaSSL replacement for OpenSSL
	------------------------------
	CyaSSL is a lightweight SSL library targeted at embedded system:
	http://www.yassl.com/yaSSL/Products-cyassl.html

	It contains a OpenSSL compatability layer which makes it possible to pretty
	much link to it instead of OpenSSL, giving a much smaller footprint.

	NOTE: At the time of writing this the current release of CyaSSL contains a
	crash bug due to some APIs libwebsocket uses. To be able to use this you will
	need to use the current HEAD in their official repository:
	https://github.com/cyassl/cyassl

	NOTE: cyassl needs to be compiled using the --enable-opensslExtra flag for
	this to work.

	Compiling libwebsockets with CyaSSL
	-----------------------------------

	cmake -DUSE_CYASSL=1
	-DCYASSL_INCLUDE_DIRS=/path/to/cyassl
	-DCYASSL_LIB=/path/to/cyassl/cyassl.a ..

	NOTE: On windows use the .lib file extension for CYASSL_LIB instead.

	Cross compiling
	---------------
	To enable cross compiling libwebsockets using CMake you need to create
	a "Toolchain file" that you supply to CMake when generating your build files.
	CMake will then use the cross compilers and build paths specified in this file
	to look for dependencies and such.

	Libwebsockets includes an example toolchain file cross-arm-linux-gnueabihf.cmake
	you can use as a starting point.

	The commandline to configure for cross with this would look like

	cmake .. -DCMAKE_INSTALL_PREFIX:PATH=/usr \
	-DCMAKE_TOOLCHAIN_FILE=../cross-arm-linux-gnueabihf.cmake \
	-DWITHOUT_EXTENSIONS=1 -DWITH_SSL=0

	The example shows how to build with no external cross lib dependencies, you
	need to proide the cross libraries otherwise.

	NOTE: start from an EMPTY build directory if you had a non-cross build in there
	before the settings will be cached and your changes ignored.

	Additional information on cross compilation with CMake:
	http://www.vtk.org/Wiki/CMake_Cross_Compiling


	Memory efficiency
	-----------------

	Embedded server-only configuration without extensions (ie, no compression
	on websocket connections), but with full v13 websocket features and http
	server, built on ARM Cortex-A9:

	Update at 8dac94d (2013-02-18)

	./configure --without-client --without-extensions --disable-debug --without-daemonize

	Context Creation, 1024 fd limit[2]: 16720 (includes 12 bytes per fd)
	Per-connection [3]: 72 bytes, +1328 during headers

	.text .rodata .data .bss
	11512 2784 288 4

	This shows the impact of the major configuration with/without options at
	13ba5bbc633ea962d46d using Ubuntu ARM on a PandaBoard ES.

	These are accounting for static allocations from the library elf, there are
	additional dynamic allocations via malloc. These are a bit old now but give
	the right idea for relative "expense" of features.

	Static allocations, ARM9
	.text .rodata .data .bss
	All (no without) 35024 9940 336 4104
	without client 25684 7144 336 4104
	without client, exts 21652 6288 288 4104
	without client, exts, debug[1] 19756 3768 288 4104
	without server 30304 8160 336 4104
	without server, exts 25382 7204 288 4104
	without server, exts, debug[1] 23712 4256 288 4104

	[1] --disable-debug only removes messages below lwsl_notice. Since that is
	the default logging level the impact is not noticable, error, warn and notice
	logs are all still there.

	[2] 1024 fd per process is the default limit (set by ulimit) in at least Fedora
	and Ubuntu. You can make significant savings tailoring this to actual expected
	peak fds, ie, at a limit of 20, context creation allocation reduces to 4432 +
	240 = 4672)

	[3] known header content is freed after connection establishment