Add cross compilation support to cmake builds

Add arm cross-compile basic support. CMake does not
support host builds. However we do host build with gn and
changing that would require an extra effort to keep all necessary
changes with Chromium upstream. Therefore let gn to perform
the host build for required tools and just feed gn with all the
build data.

Add new build steps:

* install gn into QT_HOST_PATH/libexec.
* run hostBuild project to get native architecture and compiler
* call PkgConfigHost to pass pkg-config paths to gn
* create wrapper script for host pkg-config to escape
  yocto shell pkg config exports

This change also splits gn toolchain into 3 toolchains host,target,v8
Now hostBuild provides host and v8 toolchain in case of cross compile.

The build optimizations will follow in another patch.

Fix not existing 'boot2qt' condition and enables more test on QEMU.

Note this is tested only with yocto based images.

Pick-to: dev
Task-number: QTBUG-91760
Change-Id: Ic2bea12229acc71fbd36a848e9ed4fed7e14b485
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 36 insertions, 2 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index d5133e4dc..0b55f2435 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -69,6 +69,7 @@ add_subdirectory(src/process)
 add_subdirectory(src/webenginewidgets)
 add_subdirectory(src/webenginequick)
 qt_build_repo_end()
+get_install_config(installConfig)
 
 ### NINJA
 
@@ -100,9 +101,10 @@ if(NOT Gn_FOUND)
                    -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
                    -DCMAKE_PREFIX_PATH:PATH=<INSTALL_DIR>
                    -DWEBENGINE_ROOT_BUILD_DIR=${CMAKE_CURRENT_BINARY_DIR}
-)
+    )
 endif()
 
+
 ### LIBS
 
 # on windows source path can be specified without hard drive letter,
@@ -121,11 +123,12 @@ endif()
 list(TRANSFORM featureList PREPEND "-D")
 list(APPEND libsCmakeArgs
         "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}"
-        "-DWEBENGINE_ROOT_BUILD_PATH=${CMAKE_CURRENT_BINARY_DIR}"
+        "-DWEBENGINE_ROOT_BUILD_DIR=${CMAKE_CURRENT_BINARY_DIR}"
         "-DWEBENGINE_ROOT_SOURCE_DIR=${WEBENGINE_ROOT_SOURCE_DIR}"
         "-DWEBENGINE_REPO_BUILD=TRUE"
         "${featureList}"
 )
+
 if (CMAKE_C_COMPILER_LAUNCHER)
     list(APPEND libsCmakeArgs "-DCMAKE_C_COMPILER_LAUNCHER=${CMAKE_C_COMPILER_LAUNCHER}")
 endif()
@@ -133,6 +136,10 @@ if (CMAKE_CXX_COMPILER_LAUNCHER)
     list(APPEND libsCmakeArgs "-DCMAKE_CXX_COMPILER_LAUNCHER=${CMAKE_CXX_COMPILER_LAUNCHER}")
 endif()
 
+if(QT_HOST_PATH)
+    list(APPEND libsCmakeArgs "-DQT_HOST_PATH=${QT_HOST_PATH}")
+endif()
+
 if(LINUX)
     set(cmd "${CMAKE_COMMAND} --build ${CMAKE_CURRENT_BINARY_DIR}/src")
     file(GENERATE OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/src/build.sh CONTENT "ulimit -n 4096 && ${cmd}\n")
@@ -228,3 +235,30 @@ if(NOT QT_FEATURE_framework)
         DESTINATION ${CMAKE_INSTALL_PREFIX}
     )
 endif()
+
+### CROSS BUILD SETUP
+
+# install gn for cross build
+# TODO: is this really needed, should we skip it and just build gn as host build ?
+if(LINUX AND NOT Gn_FOUND OR INSTALL_GN)
+    set(INSTALL_GN 1 CACHE INTERNAL "")
+    install(
+        PROGRAMS ${installDir}/bin/gn
+        CONFIGURATIONS ${installConfig}
+        RUNTIME DESTINATION "${INSTALL_LIBEXECDIR}"
+    )
+endif()
+
+if(CMAKE_CROSSCOMPILING)
+    externalproject_add(hostBuild
+        SOURCE_DIR  ${CMAKE_CURRENT_LIST_DIR}/src/core/configure
+        BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR}/configure
+        PREFIX      cross
+        USES_TERMINAL_BUILD ON
+        CMAKE_ARGS -DCMAKE_TOOLCHAIN_FILE=${QT_HOST_PATH}/lib/cmake/Qt6/qt.toolchain.cmake
+                   -DWEBENGINE_ROOT_BUILD_DIR=${CMAKE_CURRENT_BINARY_DIR}
+                   -DWEBENGINE_ROOT_SOURCE_DIR=${WEBENGINE_ROOT_SOURCE_DIR}
+                   -DGN_TARGET_CPU=${TEST_architecture_arch}
+    )
+    externalproject_add_stepdependencies(qtwebengine install hostBuild)
+endif()