CMake 2.8.11 or later is required.
Perl 5.6.1 or later is required. On Windows, Active State Perl has been reported to work, as has MSYS Perl. Strawberry Perl also works but it adds GCC to
PATH, which can confuse some build tools when identifying the compiler (removing
PATHshould resolve any problems). If Perl is not found by CMake, it may be configured explicitly by setting
On Windows you currently must use Ninja to build; on other platforms, it is not required, but recommended, because it makes builds faster.
If you need to build Ninja from source, then a recent version of Python is required (Python 2.7.5 works).
On Windows only, Yasm is required. If not found by CMake, it may be configured explicitly by setting
A C compiler is required. On Windows, MSVC 14 (Visual Studio 2015) or later with Platform SDK 8.1 or later are supported. Recent versions of GCC (4.8+) and Clang should work on non-Windows platforms, and maybe on Windows too. To build the tests, you also need a C++ compiler with C++11 support.
Go is required. If not found by CMake, the go executable may be configured explicitly by setting
To build the x86 and x86_64 assembly, your assembler must support AVX2 instructions and MOVBE. If using GNU binutils, you must have 2.22 or later.
Using Ninja (note the 'N' is capitalized in the cmake invocation):
mkdir build cd build cmake -GNinja .. ninja
Using Make (does not work on Windows):
mkdir build cd build cmake .. make
You usually don't need to run
cmake again after changing
files because the build scripts will detect changes to them and rebuild
Note that the default build flags in the top-level
CMakeLists.txt are for
debugging—optimisation isn't enabled. Pass
cmake to configure a release build.
If you want to cross-compile then there is an example toolchain file for 32-bit
util/. Wipe out the build directory, recreate it and run
cmake -DCMAKE_TOOLCHAIN_FILE=../util/32-bit-toolchain.cmake -GNinja ..
If you want to build as a shared library, pass
Windows, where functions need to be tagged with
dllimport when coming from a
shared library, define
BORINGSSL_SHARED_LIBRARY in any code which
the BoringSSL headers.
In order to serve environments where code-size is important as well as those
where performance is the overriding concern,
OPENSSL_SMALL can be defined to
remove some code that is especially large.
See CMake's documentation for other variables which may be used to configure the build.
Building for Android¶
It's possible to build BoringSSL with the Android NDK using CMake. This has been tested with version 10d of the NDK.
Unpack the Android NDK somewhere and export
ANDROID_NDK to point to the
directory. Then make a build directory as above and run CMake like this:
cmake -DANDROID_ABI=armeabi-v7a \ -DCMAKE_TOOLCHAIN_FILE=../third_party/android-cmake/android.toolchain.cmake \ -DANDROID_NATIVE_API_LEVEL=16 \ -GNinja ..
Once you've run that, Ninja should produce Android-compatible binaries. You
armeabi-v7a in the above with
arm64-v8a and use API level 21 or
higher to build aarch64 binaries.
For other options, see android-cmake's documentation.
Known Limitations on Windows¶
Versions of CMake since 3.0.2 have a bug in its Ninja generator that causes yasm to output warnings
yasm: warning: can open only one input file, only the last file will be processed
These warnings can be safely ignored. The cmake bug is http://www.cmake.org/Bug/view.php?id=15253.
CMake can generate Visual Studio projects, but the generated project files don't have steps for assembling the assembly language source files, so they currently cannot be used to build BoringSSL.
ARM, unlike Intel, does not have an instruction that allows applications to discover the capabilities of the processor. Instead, the capability information has to be provided by the operating system somehow.
BoringSSL will try to use
getauxval to discover the capabilities and, failing
that, will probe for NEON support by executing a NEON instruction and handling
any illegal-instruction signal. But some environments don't support that sort
of thing and, for them, it's possible to configure the CPU capabilities
at compile time.
If you define
OPENSSL_STATIC_ARMCAP then you can define any of the following
to enabling the corresponding ARM feature.
__ARM_NEON__(note that the latter is set by compilers when NEON support is enabled).
Note that if a feature is enabled in this way, but not actually supported at run-time, BoringSSL will likely crash.
Assembling ARMv8 with Clang¶
In order to support the ARMv8 crypto instructions, Clang requires that the
armv8-a+crypto. However, setting that as a general build flag
would allow the compiler to assume that crypto instructions are always
supported, even without testing for them.
It's possible to set the architecture in an assembly file using the
directive, but only very recent versions of Clang support this. If
BORINGSSL_CLANG_SUPPORTS_DOT_ARCH is defined then
.arch directives will be
used with Clang, otherwise you may need to craft acceptable assembler flags.
There are two sets of tests: the C/C++ tests and the blackbox tests. For former
are built by Ninja and can be run from the top-level directory with
go runutil/all_tests.go. The latter have to be run separately by running
Both sets of tests may also be run with
ninja -C build run_tests, but CMake
3.2 or later is required to avoid Ninja's output buffering.