[cmake, docs] Reorganize CMakeModules directory and add GentooCross toolchain (#4088)

Lightly inspired by my earlier toolchain and writeup from the PowerPC
PR.

Closes #3793

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4088
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

CMakeLists.txt

@@ -6,6 +6,7 @@ cmake_minimum_required(VERSION 3.31)
 project(yuzu)
 
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMakeModules")
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/CMakeModules/find")
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/externals/cmake-modules")
 
 set(CPM_SOURCE_CACHE ${CMAKE_SOURCE_DIR}/.cache/cpm)

CMakeModules/WindowsCopyFiles.cmake

@@ -1,39 +0,0 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
-# SPDX-License-Identifier: GPL-3.0-or-later
-
-# SPDX-FileCopyrightText: 2018 yuzu Emulator Project
-# SPDX-License-Identifier: GPL-2.0-or-later
-
-# This file provides the function windows_copy_files.
-# This is only valid on Windows.
-
-# Include guard
-if(__windows_copy_files)
-	return()
-endif()
-set(__windows_copy_files YES)
-
-# Any number of files to copy from SOURCE_DIR to DEST_DIR can be specified after DEST_DIR.
-# This copying happens post-build.
-if (CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
-    function(windows_copy_files TARGET SOURCE_DIR DEST_DIR)
-        # windows commandline expects the / to be \ so switch them
-        string(REPLACE "/" "\\\\" SOURCE_DIR ${SOURCE_DIR})
-        string(REPLACE "/" "\\\\" DEST_DIR ${DEST_DIR})
-
-        # /NJH /NJS /NDL /NFL /NC /NS /NP - Silence any output
-        # cmake adds an extra check for command success which doesn't work too well with robocopy
-        # so trick it into thinking the command was successful with the || cmd /c "exit /b 0"
-        add_custom_command(TARGET ${TARGET} POST_BUILD
-            COMMAND ${CMAKE_COMMAND} -E make_directory ${DEST_DIR}
-            COMMAND robocopy ${SOURCE_DIR} ${DEST_DIR} ${ARGN} /NJH /NJS /NDL /NFL /NC /NS /NP || cmd /c "exit /b 0"
-        )
-    endfunction()
-else()
-    function(windows_copy_files TARGET SOURCE_DIR DEST_DIR)
-        add_custom_command(TARGET ${TARGET} POST_BUILD
-            COMMAND ${CMAKE_COMMAND} -E make_directory ${DEST_DIR}
-            COMMAND cp -ra ${SOURCE_DIR}/. ${DEST_DIR}
-        )
-    endfunction()
-endif()

CMakeModules/aqt_config.ini

@@ -1,30 +0,0 @@
-# SPDX-FileCopyrightText: 2024 kleidis
-
-[aqt]
-concurrency: 2
-
-[mirrors]
-trusted_mirrors:
-    https://download.qt.io
-blacklist:
-    https://qt.mirror.constant.com
-    https://mirrors.ocf.berkeley.edu
-    https://mirrors.ustc.edu.cn
-    https://mirrors.tuna.tsinghua.edu.cn
-    https://mirrors.geekpie.club
-    https://mirrors-wan.geekpie.club
-    https://mirrors.sjtug.sjtu.edu.cn
-fallbacks:
-    https://qtproject.mirror.liquidtelecom.com/
-    https://mirrors.aliyun.com/qt/
-    https://ftp.jaist.ac.jp/pub/qtproject/
-    https://ftp.yz.yamagata-u.ac.jp/pub/qtproject/
-    https://qt-mirror.dannhauer.de/
-    https://ftp.fau.de/qtproject/
-    https://mirror.netcologne.de/qtproject/
-    https://mirrors.dotsrc.org/qtproject/
-    https://www.nic.funet.fi/pub/mirrors/download.qt-project.org/
-    https://master.qt.io/
-    https://mirrors.ukfast.co.uk/sites/qt.io/
-    https://ftp2.nluug.nl/languages/qt/
-    https://ftp1.nluug.nl/languages/qt/

CMakeModules/find/FindDiscordRPC.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 Alexandre Bouvier <contact@amb.tf>

CMakeModules/find/FindFFmpeg.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2019 Citra Emulator Project

CMakeModules/find/FindOpus.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 yuzu Emulator Project

CMakeModules/find/FindRenderDoc.cmake

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2023 Alexandre Bouvier <contact@amb.tf>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later

CMakeModules/find/FindSimpleIni.cmake

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2023 Alexandre Bouvier <contact@amb.tf>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later

CMakeModules/find/Findenet.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 Alexandre Bouvier <contact@amb.tf>

CMakeModules/find/Findgamemode.cmake

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2023 yuzu Emulator Project
 # SPDX-License-Identifier: GPL-2.0-or-later
 

CMakeModules/find/Findhttplib.cmake

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2022 Andrea Pappacoda <andrea@pappacoda.it>
 #
 # SPDX-License-Identifier: GPL-2.0-or-later

CMakeModules/find/Findlibiw.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 find_package(PkgConfig QUIET)

CMakeModules/find/Findlibusb.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 Alexandre Bouvier <contact@amb.tf>

CMakeModules/find/Findlz4.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 yuzu Emulator Project

CMakeModules/find/Findstb.cmake

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2023 Alexandre Bouvier <contact@amb.tf>
 #
 # SPDX-License-Identifier: GPL-3.0-or-later

CMakeModules/find/Findzstd.cmake

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 # SPDX-FileCopyrightText: 2022 yuzu Emulator Project

CMakeModules/toolchains/GentooCross.cmake

@@ -0,0 +1,39 @@
+# SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+set(CROSS_TARGET "" CACHE STRING "Cross-compilation target (aarch64, etc)")
+set(CROSS_PLATFORM "unknown-linux-gnu" CACHE STRING "Cross-compilation platform (e.g. unknown-linux-gnu)")
+set(CROSS_COMPILER "gcc" CACHE STRING "Cross compiler type (gcc or clang)")
+
+if (NOT CROSS_TARGET)
+    message(FATAL_ERROR "GentooCross used without a valid CROSS_TARGET")
+endif()
+
+set(prefix ${CROSS_TARGET}-${CROSS_PLATFORM})
+
+set(CMAKE_SYSROOT /usr/${prefix})
+
+if (CROSS_COMPILER STREQUAL "gcc")
+    set(CMAKE_C_COMPILER ${prefix}-gcc)
+    set(CMAKE_CXX_COMPILER ${prefix}-g++)
+elseif (CROSS_COMPILER STREQUAL "clang")
+    set(CMAKE_C_COMPILER ${prefix}-clang)
+    set(CMAKE_CXX_COMPILER ${prefix}-clang++)
+else()
+    message(FATAL_ERROR "Unsupported cross compiler type ${CROSS_COMPILER}")
+endif()
+
+# search programs in the host environment
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# search headers and libraries in the target environment
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})
+
+# sanity checks
+if (NOT IS_DIRECTORY ${CMAKE_SYSROOT})
+    message(FATAL_ERROR "Invalid sysroot ${CMAKE_SYSROOT}."
+        "Double-check your CROSS_TARGET and CROSS_PLATFORM.")
+endif()

docs/CrossCompile.md

@@ -10,3 +10,81 @@ A painless guide for cross compilation (or to test NCE) from a x86_64 system wit
 - Download Debian 13: `wget https://cdimage.debian.org/debian-cd/current/arm64/iso-cd/debian-13.0.0-arm64-netinst.iso`
 - Create a system disk: `qemu-img create -f qcow2 debian-13-arm64-ci.qcow2 30G`
 - Run the VM: `qemu-system-aarch64 -M virt -m 2G -cpu max -bios /usr/local/share/qemu/edk2-aarch64-code.fd -drive if=none,file=debian-13.0.0-arm64-netinst.iso,format=raw,id=cdrom -device scsi-cd,drive=cdrom -drive if=none,file=debian-13-arm64-ci.qcow2,id=hd0,format=qcow2 -device virtio-blk-device,drive=hd0 -device virtio-gpu-pci -device usb-ehci -device usb-kbd -device intel-hda -device hda-output -nic user,model=virtio-net-pci`
+
+## Gentoo
+
+Gentoo's cross-compilation setup is relatively easy, provided you're already familiar with portage. A [cross toolchain file](../CMakeModules/toolchains/GentooCross.cmake) is provided. Throughout this section, replace `aarch64` with whatever target architecture you desire.
+
+### Crossdev
+
+First, emerge crossdev via `sudo emerge -a sys-devel/crossdev`.
+
+Now, set up the environment depending on the target architecture; e.g.
+
+```sh
+sudo crossdev aarch64
+```
+
+### QEMU
+
+If you don't have a host Gentoo system of your target architecture, you should install a QEMU user setup for testing. To do so, enable the relevant USE flags for `app-emulation/qemu`:
+
+```txt
+app-emulation/qemu static-user qemu_user_targets_aarch64
+```
+
+To use cross-emerged shared libraries, you will also need to tell qemu where the sysroot is. You can do this with an alias:
+
+```sh
+alias qemu-aarch64="qemu-aarch64 -L /usr/aarch64-unknown-linux-gnu"
+```
+
+### Dependencies
+
+Dependencies are the same [as normal Gentoo](./Deps.md#Commands); simply replace the `emerge` command with `emerge-<target>-unknown-linux-gnu` (e.g. `emerge-aarch64-unknown-linux-gnu`). However, there are a few caveats:
+
+#### Enabling GURU
+
+Since Crossdev sysroots are effectively isolated from the system w.r.t Portage, you must manually enable GURU in your sysroot. Run the following as root:
+
+```sh
+mkdir -p /usr/aarch64-unknown-linux-gnu/etc/portage/repos.conf
+cat << EOF > /usr/aarch64-unknown-linux-gnu/etc/portage/repos.conf/guru.conf
+[guru]
+location = /var/db/repos/guru
+auto-sync = no
+priority = 1
+EOF
+```
+
+#### Package Errata
+
+Crossdev is not perfect, and you may face some challenges with package that are not properly keyworded or have issues on specific architectures. These behaviors are, unfortunately, not well documented, and certain build systems such as Meson--and certain troublesome packages like GTK--are generally unfriendly towards cross-compilation.
+
+Thus, it may be desirable to emerge a minimal set of dependencies and allow Eden's build system to handle the rest for you. At a minimum, you *only* need standard system libraries (Crossdev does this for you) and Qt:
+
+```sh
+sudo emerge-aarch64-unknown-linux-gnu dev-qt/qtbase:6 dev-qt/qtcharts:6
+```
+
+From here, CPMUtil will take care of everything else. For extra insurance, you may want to set `-DCPMUTIL_FORCE_BUNDLED=ON` in your configure command.
+
+### Building
+
+From here, building is relatively standard. The [cross toolchain file](../CMakeModules/toolchains/GentooCross.cmake) contains a few additional configurations, but generally all you need to do is set `CROSS_TARGET` and `CMAKE_TOOLCHAIN_FILE`. Disabling OpenGL is strongly recommended as well.
+
+```sh
+cmake -S . -B build/aarch64 -DCMAKE_TOOLCHAIN_FILE=CMakeModules/toolchains/GentooCross.cmake -GNinja -DCROSS_TARGET=aarch64 -DENABLE_OPENGL=OFF
+```
+
+With that done, you can build as normal:
+
+```sh
+cmake --build build/aarch64
+```
+
+And finally, run the compiled executable with QEMU!
+
+```sh
+qemu-aarch64 build/aarch64/bin/eden
+```