diff options
author | David Seifert <soap@gentoo.org> | 2019-10-05 13:58:48 (GMT) |
---|---|---|
committer | David Seifert <soap@gentoo.org> | 2019-10-05 13:58:48 (GMT) |
commit | b96832a44b4994cafc824f200d69232d79f30d81 (patch) | |
tree | 233689da32598af6562186530438368f5ec07a7a /googletest/docs | |
parent | 5126ff48d9ac54828d1947d1423a5ef2a8efee3b (diff) | |
download | googletest-b96832a44b4994cafc824f200d69232d79f30d81.zip googletest-b96832a44b4994cafc824f200d69232d79f30d81.tar.gz googletest-b96832a44b4994cafc824f200d69232d79f30d81.tar.bz2 |
Add documentation for pkg-config in cross-compilation settingsrefs/pull/2491/head
Diffstat (limited to 'googletest/docs')
-rw-r--r-- | googletest/docs/pkgconfig.md | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/googletest/docs/pkgconfig.md b/googletest/docs/pkgconfig.md index 6dc0673..d5f3614 100644 --- a/googletest/docs/pkgconfig.md +++ b/googletest/docs/pkgconfig.md @@ -139,3 +139,81 @@ export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig ``` pkg-config will also try to look in `PKG_CONFIG_PATH` to find `gtest_main.pc`. + +### Using pkg-config in a cross-compilation setting + +Pkg-config can be used in a cross-compilation setting too. To do this, let's +assume the final prefix of the cross-compiled installation will be `/usr`, +and your sysroot is `/home/MYUSER/sysroot`. Configure and install GTest using + +``` +mkdir build && cmake -DCMAKE_INSTALL_PREFIX=/usr .. +``` + +Install into the sysroot using `DESTDIR`: + +``` +make -j install DESTDIR=/home/MYUSER/sysroot +``` + +Before we continue, it is recommended to **always** define the following two +variables for pkg-config in a cross-compilation setting: + +``` +export PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=yes +export PKG_CONFIG_ALLOW_SYSTEM_LIBS=yes +``` + +otherwise `pkg-config` will filter `-I` and `-L` flags against standard +prefixes such as `/usr` (see https://bugs.freedesktop.org/show_bug.cgi?id=28264#c3 +for reasons why this stripping needs to occur usually). + +If you look at the generated pkg-config file, it will look something like + +``` +libdir=/usr/lib64 +includedir=/usr/include + +Name: gtest +Description: GoogleTest (without main() function) +Version: 1.10.0 +URL: https://github.com/google/googletest +Libs: -L${libdir} -lgtest -lpthread +Cflags: -I${includedir} -DGTEST_HAS_PTHREAD=1 -lpthread +``` + +Notice that the sysroot is not included in `libdir` and `includedir`! If you +try to run `pkg-config` with the correct +`PKG_CONFIG_LIBDIR=/home/MYUSER/sysroot/usr/lib64/pkgconfig` against this `.pc` +file, you will get + +``` +$ pkg-config --cflags gtest +-DGTEST_HAS_PTHREAD=1 -lpthread -I/usr/include +$ pkg-config --libs gtest +-L/usr/lib64 -lgtest -lpthread +``` + +which is obviously wrong and points to the `CBUILD` and not `CHOST` root. +In order to use this in a cross-compilation setting, we need to tell +pkg-config to inject the actual sysroot into `-I` and `-L` variables. Let us +now tell pkg-config about the actual sysroot + +``` +export PKG_CONFIG_DIR= +export PKG_CONFIG_SYSROOT_DIR=/home/MYUSER/sysroot +export PKG_CONFIG_LIBDIR=${PKG_CONFIG_SYSROOT_DIR}/usr/lib64/pkgconfig +``` + +and running `pkg-config` again we get + +``` +$ pkg-config --cflags gtest +-DGTEST_HAS_PTHREAD=1 -lpthread -I/home/MYUSER/sysroot/usr/include +$ pkg-config --libs gtest +-L/home/MYUSER/sysroot/usr/lib64 -lgtest -lpthread +``` + +which contains the correct sysroot now. For a more comprehensive guide to +also including `${CHOST}` in build system calls, see the excellent tutorial +by Diego Elio Pettenò: https://autotools.io/pkgconfig/cross-compiling.html |