How to use vcpkg with cross-compilation

[sshcrack]

(Trying to work out a fix, this is not working as intended!)

Hi!
This is a quick little guide to get vpckg up and running with cross compilation.

Requirements

• vcpkg
• RPI-Tools / Sysroot

Setup Triplet

<VCPKG_ROOT>/triplets/community/arm64-rpi.cmake

set(VCPKG_TARGET_ARCHITECTURE arm64)
set(VCPKG_CRT_LINKAGE dynamic)
set(VCPKG_LIBRARY_LINKAGE static)

set(VCPKG_CMAKE_SYSTEM_NAME Linux)

set(VCPKG_CHAINLOAD_TOOLCHAIN_FILE <Put your toolchain file here as it was instructed in the wiki>) #Set this toolchain file

Modify toolchain file

You'll need to modify the original toolchain file that you created with the wiki. Remove the line starting with set(CMAKE_FIND_ROOT_PATH. You'll also need to append set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY) at the end of the file.
It should now look something like this:

set(CMAKE_VERBOSE_MAKEFILE ON)
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_SYSTEM_PROCESSOR aarch64)

set(tools <path to toolchain. for e.g $ENV{HOME}/cmake-test/tools/cross-pi-gcc-12.2.0-64>) # warning change toolchain path here.
set(rootfs_dir $ENV{HOME}/cmake-test/rootfs)

# set(CMAKE_FIND_ROOT_PATH ${rootfs_dir}) UNCOMMENT THIS LINE!!!
set(CMAKE_SYSROOT ${rootfs_dir})

set(CMAKE_LIBRARY_ARCHITECTURE aarch64-linux-gnu)
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fPIC -Wl,-rpath-link,${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE} -L${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE}")
set(CMAKE_C_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -Wl,-rpath-link,${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE} -L${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -Wl,-rpath-link,${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE} -L${CMAKE_SYSROOT}/usr/lib/${CMAKE_LIBRARY_ARCHITECTURE}")

## Compiler Binary 
SET(BIN_PREFIX ${tools}/bin/aarch64-linux-gnu)

SET (CMAKE_C_COMPILER ${BIN_PREFIX}-gcc)
SET (CMAKE_CXX_COMPILER ${BIN_PREFIX}-g++ )
SET (CMAKE_LINKER ${BIN_PREFIX}-ld 
            CACHE STRING "Set the cross-compiler tool LD" FORCE)
SET (CMAKE_AR ${BIN_PREFIX}-ar 
            CACHE STRING "Set the cross-compiler tool AR" FORCE)
SET (CMAKE_NM {BIN_PREFIX}-nm 
            CACHE STRING "Set the cross-compiler tool NM" FORCE)
SET (CMAKE_OBJCOPY ${BIN_PREFIX}-objcopy 
            CACHE STRING "Set the cross-compiler tool OBJCOPY" FORCE)
SET (CMAKE_OBJDUMP ${BIN_PREFIX}-objdump 
            CACHE STRING "Set the cross-compiler tool OBJDUMP" FORCE)
SET (CMAKE_RANLIB ${BIN_PREFIX}-ranlib 
            CACHE STRING "Set the cross-compiler tool RANLIB" FORCE)
SET (CMAKE_STRIP {BIN_PREFIX}-strip 
            CACHE STRING "Set the cross-compiler tool RANLIB" FORCE)

set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY) #Add this line

Configuring

Now use the following command to configure your project:

# in your build directory
cmake -DCMAKE_TOOLCHAIN_FILE=<something>/vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=arm64-rpi -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=<something>/rpi-cross-compile/PI.cmake ..

I'm very new to writing guides. I would be happy to receive feedback!

[sshcrack]

Hey, maybe someone can help:
When I comment the line set(CMAKE_FIND_ROOT_PATH ${rootfs_dir}) vcpkg does its job and the project can be configured.
But when I try to build the project using make, I'm getting these errors:

 /usr/bin/ld../vcpkg_installed/arm64-rpi/debug/lib/libspdlogd.a(spdlog.cpp.o): Relocations in generic ELF (EM: 183)

Now this seems like the wrong linker is being used. I guess this is achieved by CMAKE_FIND_ROOT_PATH right?
Anyway, it isn't working :/

[sshcrack]

Alright got a fix and updated the guide