1Build System for Native Client SDK examples
2===========================================
3
4The examples and libraries that ship with the Native Client SDK use a
5build system based on GNU Make.
6
7Each example or library is contained in its own directory along with a
8Makefile. The Makefiles are capable of building Native Client
9applications and libraries using any of the available toolchains as well
10as building host applications with the host's toolchain. In order to
11keep the top-level Makefiles simple, most of actual build rules are
12specified in as set of shared rules files in the $NACL_SDK_ROOT/tools
13directory.
14
15This document describes some of the variables and macros used by in the
16build system.  For more details please see the .mk files in the tools
17folder.
18
19Using the build system for new projects
20--------------------------------------
21
22It is perfectly possible to use the included build system for projects
23outside of the Native Client SDK.  A good starting point for doing this
24would be to copy the Makefile from the hello_world example.  In most
25simple cases the only changes needed are to update the SOURCES and
26TARGET variables.
27
28User Variables
29--------------
30
31TARGET
32  This variable holds the name of your project.  Normally this is the
33  basename of the library or executable which is the final target.
34
35SOURCES
36  The list of sources to be built.  In most cases this list is passed to
37  the compile and link macros.
38
39VALID_TOOLCHAINS
40  This variable can be used to control which toolchains are supported by
41  the project.  Valid entries for this list are: newlib, glibc, pnacl,
42  linux, mac, win.  The default value is: "newlib glibc pnacl".
43
44NACL_SDK_ROOT
45  Optionally force the build system to use a certain location for the
46  Native Client SDK. If not set within the Makefile the $NACL_SDK_ROOT
47  environment variable will by used. It is an error if this variable is
48  neither set within the Makefile nor in the environment.
49
50Macros / Rules
51--------------
52
53The following macros can be used in the Makefiles to generate the rules
54for building the various kinds types of target.  These are designed to
55be used via the 'call' macro.  e.g.  $(call COMPILE_RULE,$(SOURCES))
56
57COMPILE_RULE
58  This rule is used to build object files from a list of sources.
59
60SO_RULE
61  Used to build shared objects from a list of sources.
62
63LIB_RULE
64  Used to build static libraries from a list of sources.
65
66NMF_RULE
67  Used to build nmf metadata file from a native client executable (or
68  set of executables). This is needed in order to run the executable in
69  chrome.
70
71HTML_RULE
72  Used to build both html and nmf files from a native client executable
73  (or set of executables) which will allow the executable to be run
74  in chrome.
75
76For more information on how to use these rules in your Makefile see
77the shared Makefiles in the tools folders:
78
79common.mk
80  Top level shared rules file that include the toolchain specific
81  rules.
82
83nacl_gcc.mk
84  Rules for building using the gcc-based NaCl toolchains.
85
86nacl_llvm.mk
87  Rules for building using the llvm-based PNaCl toolchains.
88
89host_gcc.mk
90  Rules for building using the linux/mac host gcc toolchain.
91
92host_vc.mk
93  Rules for building using the windows Visual Studio toolchain.
94
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