A cross compilation setup by Claude for loongarch64 to check that things build.

CMakeLists.txt

@@ -1499,78 +1499,81 @@ elseif(WIN32)
 	set(TargetBin PPSSPPWindows)
 elseif(LIBRETRO)
 else()
-	if(GOLD)
+	if(SDL2_FOUND OR SDL2Fwk)
-		set(TargetBin PPSSPPGold)
+		if(GOLD)
-	else()
+			set(TargetBin PPSSPPGold)
-		set(TargetBin PPSSPPSDL)
+		else()
-	endif()
+			set(TargetBin PPSSPPSDL)
-	# Require SDL
-	add_compile_definitions(SDL)
-	list(APPEND nativeExtra
-		SDL/SDLJoystick.h
-		SDL/SDLJoystick.cpp
-		SDL/SDLMain.cpp
-		SDL/SDLGLGraphicsContext.cpp
-	)
-	if(NOT USE_LIBNX)
-		list(APPEND nativeExtra
-			SDL/SDLVulkanGraphicsContext.cpp
-		)
-	endif()
-	if(SDL2_ttf_FOUND OR
-		(SDL2_ttf_PKGCONFIG_FOUND AND
-			SDL2_ttf_PKGCONFIG_VERSION VERSION_GREATER_EQUAL "2.0.18"))
-		add_compile_definitions(USE_SDL2_TTF)
-		if(FONTCONFIG_FOUND)
-			add_compile_definitions(USE_SDL2_TTF_FONTCONFIG)
-			list(APPEND nativeExtraLibs Fontconfig::Fontconfig)
 		endif()
-	elseif(SDL2_ttf_PKGCONFIG_FOUND)
+		add_compile_definitions(SDL)
-		message(WARNING "Found SDL2_ttf <2.0.18 - this is too old, falling back to atlas")
-	endif()
-	if(SDL2_ttf_FOUND)
-		list(APPEND nativeExtraLibs SDL2_ttf::SDL2_ttf)
-	elseif(SDL2_ttf_PKGCONFIG_FOUND)
-		list(APPEND nativeExtraLibs PkgConfig::SDL2_ttf_PKGCONFIG)
-	endif()
-	if(APPLE)
 		list(APPEND nativeExtra
-		SDL/SDLMain.h
+			SDL/SDLJoystick.h
-		SDL/SDLMain.mm
+			SDL/SDLJoystick.cpp
-		SDL/SDLCocoaMetalLayer.h
+			SDL/SDLMain.cpp
-		SDL/SDLCocoaMetalLayer.mm
+			SDL/SDLGLGraphicsContext.cpp
-		SDL/CocoaBarItems.mm
+		)
-		SDL/CocoaBarItems.h
+		if(NOT USE_LIBNX)
-		SDL/PPSSPPAboutViewController.m
+			list(APPEND nativeExtra
-		SDL/PPSSPPAboutViewController.h
+				SDL/SDLVulkanGraphicsContext.cpp
-		SDL/MacCameraHelper.mm
+			)
-		Common/Battery/AppleBatteryClient.m
+		endif()
-		UI/PSPNSApplicationDelegate.mm
+		if(SDL2_ttf_FOUND OR
-		UI/PSPNSApplicationDelegate.h)
+			(SDL2_ttf_PKGCONFIG_FOUND AND
-
+				SDL2_ttf_PKGCONFIG_VERSION VERSION_GREATER_EQUAL "2.0.18"))
-		# TODO
+			add_compile_definitions(USE_SDL2_TTF)
-		# set_source_files_properties(SDL/SDLMain.mm PROPERTIES COMPILE_FLAGS -fobjc-arc)
+			if(FONTCONFIG_FOUND)
-
+				add_compile_definitions(USE_SDL2_TTF_FONTCONFIG)
-		set_source_files_properties(Core/Util/DarwinFileSystemServices.mm
+				list(APPEND nativeExtraLibs Fontconfig::Fontconfig)
-			UI/PSPNSApplicationDelegate.mm
+			endif()
-			SDL/CocoaMetalLayer.mm
+		elseif(SDL2_ttf_PKGCONFIG_FOUND)
+			message(WARNING "Found SDL2_ttf <2.0.18 - this is too old, falling back to atlas")
+		endif()
+		if(SDL2_ttf_FOUND)
+			list(APPEND nativeExtraLibs SDL2_ttf::SDL2_ttf)
+		elseif(SDL2_ttf_PKGCONFIG_FOUND)
+			list(APPEND nativeExtraLibs PkgConfig::SDL2_ttf_PKGCONFIG)
+		endif()
+		if(APPLE)
+			list(APPEND nativeExtra
+			SDL/SDLMain.h
+			SDL/SDLMain.mm
+			SDL/SDLCocoaMetalLayer.h
+			SDL/SDLCocoaMetalLayer.mm
 			SDL/CocoaBarItems.mm
+			SDL/CocoaBarItems.h
 			SDL/PPSSPPAboutViewController.m
+			SDL/PPSSPPAboutViewController.h
 			SDL/MacCameraHelper.mm
 			Common/Battery/AppleBatteryClient.m
-			Common/Render/Text/draw_text_cocoa.mm
+			UI/PSPNSApplicationDelegate.mm
-			PROPERTIES COMPILE_FLAGS -fobjc-arc)
+			UI/PSPNSApplicationDelegate.h)
-		list(APPEND nativeExtraLibs ${COCOA_LIBRARY} ${QUARTZ_CORE_LIBRARY} ${IOKIT_LIBRARY} "-framework AVFoundation" "-framework CoreMedia" "-framework CoreVideo")
 
-		if(USE_SYSTEM_LIBSDL2)
+			# TODO
-			list(APPEND nativeExtraLibs SDL2::SDL2)
+			# set_source_files_properties(SDL/SDLMain.mm PROPERTIES COMPILE_FLAGS -fobjc-arc)
+
+			set_source_files_properties(Core/Util/DarwinFileSystemServices.mm
+				UI/PSPNSApplicationDelegate.mm
+				SDL/CocoaMetalLayer.mm
+				SDL/CocoaBarItems.mm
+				SDL/PPSSPPAboutViewController.m
+				SDL/MacCameraHelper.mm
+				Common/Battery/AppleBatteryClient.m
+				Common/Render/Text/draw_text_cocoa.mm
+				PROPERTIES COMPILE_FLAGS -fobjc-arc)
+			list(APPEND nativeExtraLibs ${COCOA_LIBRARY} ${QUARTZ_CORE_LIBRARY} ${IOKIT_LIBRARY} "-framework AVFoundation" "-framework CoreMedia" "-framework CoreVideo")
+
+			if(USE_SYSTEM_LIBSDL2)
+				list(APPEND nativeExtraLibs SDL2::SDL2)
+			else()
+				list(APPEND nativeExtraLibs ${SDL2Fwk})
+			endif()
+		elseif(USING_EGL)
+			list(APPEND nativeExtraLibs pthread SDL2::SDL2)
 		else()
-			list(APPEND nativeExtraLibs ${SDL2Fwk})
+			list(APPEND nativeExtraLibs SDL2::SDL2)
 		endif()
-	elseif(USING_EGL)
+	elseif(NOT CMAKE_CROSSCOMPILING)
-		list(APPEND nativeExtraLibs pthread SDL2::SDL2)
+		message(FATAL_ERROR "SDL2 not found - required for this platform")
-	else()
-		list(APPEND nativeExtraLibs SDL2::SDL2)
 	endif()
 endif()
 

b.sh

@@ -38,6 +38,11 @@ do
 		--rpi64)
 			CMAKE_ARGS="-DCMAKE_TOOLCHAIN_FILE=cmake/Toolchains/raspberry.armv8.cmake ${CMAKE_ARGS}"
 			;;
+		--loongarch64)
+			CMAKE_ARGS="-DCMAKE_TOOLCHAIN_FILE=cmake/Toolchains/loongarch64-linux-gnu.cmake -DHEADLESS=ON -DUSE_SYSTEM_LIBPNG=OFF -DUSE_SYSTEM_LIBSDL2=OFF ${CMAKE_ARGS}"
+			TARGET_OS=loongarch64
+			LOONGARCH64_BUILD=1
+			;;
 		--android) CMAKE_ARGS="-DCMAKE_TOOLCHAIN_FILE=android/android.toolchain.cmake ${CMAKE_ARGS}"
 			TARGET_OS=Android
 			PACKAGE=1
@@ -121,6 +126,33 @@ set -e
 echo Building with $CORES_COUNT threads
 
 mkdir -p ${BUILD_DIR}
+
+# For loongarch64 cross-compilation, build a comprehensive GL/GLX stub into
+# <build>/stublibs/libGL.so so GLEW's static archive can resolve its symbols
+# via PLT entries (a direct B26 branch to address 0 overflows on LoongArch).
+# This stub is always (re)generated to pick up any new needed symbols.
+if [ ! -z "$LOONGARCH64_BUILD" ]; then
+	STUB_DIR=${BUILD_DIR}/stublibs
+	STUB_GL=${STUB_DIR}/libGL.so
+	mkdir -p "${STUB_DIR}"
+	STUB_C=$(mktemp /tmp/gl_stub_XXXXXX.c)
+	echo "/* Loongarch64 GL/GLX stub - cross-compilation only */" > "$STUB_C"
+	# Collect all T (exported) symbols from GL/GLX libs, deduplicate, emit stubs
+	{
+		for lib in /usr/lib/x86_64-linux-gnu/libGL.so.1 \
+		           /usr/lib/x86_64-linux-gnu/libGLX.so.0 \
+		           /usr/lib/x86_64-linux-gnu/libGLdispatch.so.0; do
+			[ -f "$lib" ] && nm -D "$lib" 2>/dev/null | awk '/^[0-9a-f]+ T /{ print $3 }'
+		done
+		# Always include the minimal GLX symbols GLEW directly references
+		printf '%s\n' glXGetProcAddressARB glXGetClientString glXQueryVersion \
+		              glBindTexture glGetString glGetIntegerv
+	} | sort -u | awk '{ print "void "$1"(void){}" }' >> "$STUB_C"
+	loongarch64-linux-gnu-gcc-14 -shared -fPIC -Wno-implicit-function-declaration \
+		-o "${STUB_GL}" "$STUB_C"
+	rm "$STUB_C"
+fi
+
 pushd ${BUILD_DIR}
 
 cmake $CMAKE_ARGS ..

cmake/Toolchains/loongarch64-linux-gnu.cmake

@@ -0,0 +1,40 @@
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR loongarch64)
+
+set(CMAKE_C_COMPILER loongarch64-linux-gnu-gcc-14)
+set(CMAKE_CXX_COMPILER loongarch64-linux-gnu-g++-14)
+set(CMAKE_ASM_COMPILER loongarch64-linux-gnu-gcc-14)
+
+set(CMAKE_FIND_ROOT_PATH /usr/loongarch64-linux-gnu)
+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)
+
+# No X11 in the sysroot; disable the X11 Vulkan path to avoid include-dir errors.
+set(USING_X11_VULKAN OFF CACHE BOOL "" FORCE)
+
+# Bypass find_package(OpenGL REQUIRED).  A stub libGL.so is required so that
+# GLEW's static archive can be linked via PLT entries (direct B26 branches to
+# address 0 would overflow on LoongArch).
+#
+# Primary: run cmake/scripts/setup-loongarch64-cross.sh (sudo) once — it
+#          installs the stub + GL headers into the sysroot.
+# Fallback: the stub can also sit in <build-dir>/stublibs/libGL.so;
+#           b.sh --loongarch64 creates this automatically on first run.
+set(OPENGL_LIBRARIES GL CACHE STRING "" FORCE)
+set(CMAKE_EXE_LINKER_FLAGS
+    "${CMAKE_EXE_LINKER_FLAGS} -L${CMAKE_BINARY_DIR}/stublibs"
+    CACHE STRING "" FORCE)
+
+# Allow CMake's compile-check programs to run via QEMU.
+# The /lib64 symlink is created by the setup script; without it, pass -L
+# explicitly so QEMU can find the loongarch64 dynamic linker.
+if(EXISTS "/lib64/ld-linux-loongarch-lp64d.so.1")
+    set(CMAKE_CROSSCOMPILING_EMULATOR "qemu-loongarch64-static"
+        CACHE STRING "" FORCE)
+else()
+    set(CMAKE_CROSSCOMPILING_EMULATOR
+        "qemu-loongarch64-static;-L;/usr/loongarch64-linux-gnu"
+        CACHE STRING "" FORCE)
+endif()

cmake/scripts/setup-loongarch64-cross.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+# Sets up the loongarch64 cross-compilation environment.
+# Run once with sudo.  After this, ./b.sh --loongarch64 works on a fresh checkout.
+
+set -e
+
+SYSROOT=/usr/loongarch64-linux-gnu
+CROSS_GCC=loongarch64-linux-gnu-gcc-14
+
+if ! command -v $CROSS_GCC &>/dev/null; then
+    echo "Error: $CROSS_GCC not found. Install it first:"
+    echo "  sudo apt install gcc-14-loongarch64-linux-gnu g++-14-loongarch64-linux-gnu binutils-loongarch64-linux-gnu"
+    exit 1
+fi
+
+if [ "$(id -u)" -ne 0 ]; then
+    echo "This script must be run with sudo."
+    exit 1
+fi
+
+# ── OpenGL headers ───────────────────────────────────────────────────────────
+# GL headers are platform-independent C headers; copy from the host.
+echo "Installing GL headers into sysroot..."
+mkdir -p $SYSROOT/include/GL
+for h in gl.h glext.h glcorearb.h; do
+    [ -f /usr/include/GL/$h ] && cp /usr/include/GL/$h $SYSROOT/include/GL/ && echo "  $h"
+done
+
+# ── GL stub library ──────────────────────────────────────────────────────────
+# Generate a loongarch64 libGL.so that exports all symbols from the host
+# libGL so that GLEW's static archive can be linked via PLT entries (a direct
+# B26 branch to address 0 would overflow on LoongArch).
+echo "Generating libGL.so stub..."
+
+HOST_GL=""
+for candidate in \
+        /usr/lib/x86_64-linux-gnu/libGL.so.1 \
+        /usr/lib/x86_64-linux-gnu/libGL.so \
+        /usr/lib/libGL.so.1 ; do
+    [ -f "$candidate" ] && HOST_GL="$candidate" && break
+done
+
+STUB_C=$(mktemp /tmp/gl_stub_XXXXXX.c)
+echo "/* Loongarch64 GL/GLX stub - for cross-compilation only */" > "$STUB_C"
+echo "void __loongarch64_gl_placeholder(void) {}" >> "$STUB_C"
+
+if [ -n "$HOST_GL" ]; then
+    nm -D "$HOST_GL" 2>/dev/null | awk '/^[0-9a-f]+ T /{ print "void "$3"(void){}" }' >> "$STUB_C"
+    echo "  Extracted symbols from $HOST_GL"
+fi
+# Always include the minimal set GLEW needs (in case host GL wasn't found)
+for sym in glXGetProcAddressARB glXGetClientString glXQueryVersion \
+           glBindTexture glGetString glGetIntegerv glGetError; do
+    grep -q "void ${sym}(" "$STUB_C" || echo "void ${sym}(void){}" >> "$STUB_C"
+done
+
+$CROSS_GCC -shared -fPIC -Wno-implicit-function-declaration \
+    -o $SYSROOT/lib/libGL.so "$STUB_C"
+rm "$STUB_C"
+echo "  Installed to $SYSROOT/lib/libGL.so"
+
+# ── Dynamic linker symlink ───────────────────────────────────────────────────
+# Without this, binfmt_misc can't find the loongarch64 dynamic linker.
+LD_LINUX=$SYSROOT/lib/ld-linux-loongarch-lp64d.so.1
+if [ -f "$LD_LINUX" ]; then
+    mkdir -p /lib64
+    ln -sf "$LD_LINUX" /lib64/ld-linux-loongarch-lp64d.so.1
+    echo "Created /lib64/ld-linux-loongarch-lp64d.so.1 -> $LD_LINUX"
+fi
+
+echo ""
+echo "Setup complete."
+echo "Build:  ./b.sh --loongarch64"
+echo "Run:    qemu-loongarch64-static -L $SYSROOT <binary>"
+echo "  (after setup the /lib64 symlink lets you run loongarch64 binaries directly)"