Notify about cross build option upon failure.

Tell the user to use CMAKE_TOOLCHAIN_FILE upon failure.
.
Cleanup detectOperatingSystem. Should be the same but adding
GNU and kFreeBSD from Debian and filtering out pre OS X Apple.
.
libaio is linux only. Also check for the correct header since
aio.h is the POSIX one. Both are in /usr/include/ anyway.
Only build core if (Linux AND NOT AIO_FOUND) == false.
.
Use Unix for GTK and X11. Macs has gtk-quartzs and xquartz or native X11.
*BSD, linux, etc should have both.

cmake/BuildParameters.cmake

@@ -80,7 +80,11 @@ include(TargetArch)
 target_architecture(PCSX2_TARGET_ARCHITECTURES)
 if(${PCSX2_TARGET_ARCHITECTURES} MATCHES "x86_64" OR ${PCSX2_TARGET_ARCHITECTURES} MATCHES "i386")
 	if(${PCSX2_TARGET_ARCHITECTURES} MATCHES "x86_64" AND (CMAKE_BUILD_TYPE MATCHES "Release" OR PACKAGE_MODE))
-		message(FATAL_ERROR "The code for ${PCSX2_TARGET_ARCHITECTURES} support is not ready yet.")
+		message(FATAL_ERROR "
+        The code for ${PCSX2_TARGET_ARCHITECTURES} support is not ready yet.
+        For now compile with -DCMAKE_TOOLCHAIN_FILE=cmake/linux-compiler-i386-multilib.cmake
+        or with
+        --cross-multilib passed to build.sh")
 	endif()
 	message(STATUS "Compiling a ${PCSX2_TARGET_ARCHITECTURES} build on a ${CMAKE_HOST_SYSTEM_PROCESSOR} host.")
 else()

cmake/Pcsx2Utils.cmake

@@ -7,42 +7,34 @@
 # On linux, it also set a flag for specific distribution (ie Fedora)
 #-------------------------------------------------------------------------------
 function(detectOperatingSystem)
-    # nothing detected yet
-    set(MacOSX FALSE PARENT_SCOPE)
-    set(Windows FALSE PARENT_SCOPE)
-    set(Linux FALSE PARENT_SCOPE)
-    set(Fedora FALSE PARENT_SCOPE)
-
-    # check if we are on Linux
-    if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-        set(Linux TRUE PARENT_SCOPE)
-
-        if (EXISTS /etc/os-release)
-            # Read the file without CR character
-            file(STRINGS /etc/os-release OS_RELEASE)
-            if ("${OS_RELEASE}" MATCHES "^.*ID=fedora.*$")
-                set(Fedora TRUE PARENT_SCOPE)
-                message(STATUS "Build Fedora specific")
-            endif()
-            if ("${OS_RELEASE}" MATCHES "^.*ID=.*suse.*$")
-                set(openSUSE TRUE PARENT_SCOPE)
-                add_definitions(-DopenSUSE)
-                message(STATUS "Build openSUSE specific")
-            endif()
-        endif()
-    endif(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-
-    # check if we are on MacOSX
-    if(APPLE)
-        message(WARNING "Mac OS X isn't supported, build will most likely fail")
-        set(MacOSX TRUE PARENT_SCOPE)
-    endif(APPLE)
-
-    # check if we are on Windows
-    if(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
+    if(WIN32)
         set(Windows TRUE PARENT_SCOPE)
-    endif(${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
-endfunction(detectOperatingSystem)
+    elseif(UNIX AND APPLE)
+        # No easy way to filter out iOS.
+        message(WARNING "OS X/iOS isn't supported, the build will most likely fail")
+        set(MacOSX TRUE PARENT_SCOPE)
+    elseif(UNIX)
+        if(CMAKE_SYSTEM_NAME MATCHES "Linux")
+            set(Linux TRUE PARENT_SCOPE)
+            if (EXISTS /etc/os-release)
+                # Read the file without CR character
+                file(STRINGS /etc/os-release OS_RELEASE)
+                if("${OS_RELEASE}" MATCHES "^.*ID=fedora.*$")
+                    set(Fedora TRUE PARENT_SCOPE)
+                    message(STATUS "Build Fedora specific")
+                elseif("${OS_RELEASE}" MATCHES "^.*ID=.*suse.*$")
+                    set(openSUSE TRUE PARENT_SCOPE)
+                    add_definitions(-DopenSUSE)
+                    message(STATUS "Build openSUSE specific")
+                endif()
+            endif()
+        elseif(CMAKE_SYSTEM_NAME MATCHES "kFreeBSD")
+            set(kFreeBSD TRUE PARENT_SCOPE)
+        elseif(CMAKE_SYSTEM_NAME STREQUAL "GNU")
+            set(GNU TRUE PARENT_SCOPE)
+        endif()
+    endif()
+endfunction()
 
 function(write_svnrev_h)
     find_package(Git)

cmake/SearchForStuff.cmake

@@ -32,7 +32,9 @@ include(FindLibc)
 
 ## Use CheckLib package to find module
 include(CheckLib)
-check_lib(AIO aio aio.h)
+if(Linux)
+    check_lib(AIO aio libaio.h)
+endif()
 check_lib(EGL EGL EGL/egl.h)
 check_lib(GLESV2 GLESv2 GLES3/gl3ext.h) # NOTE: looking for GLESv3, not GLESv2
 check_lib(PORTAUDIO portaudio portaudio.h pa_linux_alsa.h)
@@ -46,7 +48,7 @@ else()
     find_package(SDL)
 endif()
 
-if (Linux)
+if(UNIX)
     find_package(X11)
     # Most plugins (if not all) and PCSX2 core need gtk2, so set the required flags
     if (GTK3_API)
@@ -63,7 +65,7 @@ endif()
 #----------------------------------------
 #		    Use system include
 #----------------------------------------
-if(Linux)
+if(UNIX)
 	if(GTK2_FOUND)
 		include_directories(${GTK2_INCLUDE_DIRS})
     elseif(GTK3_FOUND)

cmake/SelectPcsx2Plugins.cmake

@@ -56,7 +56,7 @@ endif()
 #           -aio
 #---------------------------------------
 # Common dependancy
-if(wxWidgets_FOUND AND ZLIB_FOUND AND common_libs AND AIO_FOUND)
+if(wxWidgets_FOUND AND ZLIB_FOUND AND common_libs AND NOT (Linux AND NOT AIO_FOUND))
     set(pcsx2_core TRUE)
 elseif(NOT EXISTS "${CMAKE_SOURCE_DIR}/pcsx2")
     set(pcsx2_core FALSE)
@@ -66,7 +66,7 @@ else()
     message(STATUS "${msg_dep_pcsx2}")
 endif()
 # Linux need also gtk2
-if(Linux AND pcsx2_core AND NOT GTKn_FOUND)
+if(UNIX AND pcsx2_core AND NOT GTKn_FOUND)
     set(pcsx2_core FALSE)
     message(STATUS "Skip build of pcsx2 core: miss some dependencies")
     message(STATUS "${msg_dep_pcsx2}")

plugins/zerogs/CMakeLists.txt

@@ -4,4 +4,4 @@
 # zerogs plugin opengl
 if(UNIX)
 	add_subdirectory(opengl)
-endif(UNIX)
+endif()