Update cross.cmake

cmake/cross.cmake

@@ -1,26 +1,23 @@
-# the name of the target operating system
+# 示例：
+# ccmake .. -DCOMPILER=mipsel-linux -DCMAKE_SYSTEM_PROCESSOR=mips32 -DCMAKE_TOOLCHAIN_FILE=../cmake/cross.cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON -G Ninja -DCMAKE_BUILD_TYPE=Release
+# ccmake .. -DCOMPILER=aarch64-linux -DCMAKE_SYSTEM_PROCESSOR=aarch64 -DCMAKE_TOOLCHAIN_FILE=../cmake/cross.cmake -DCMAKE_POSITION_INDEPENDENT_CODE=ON -G Ninja -DCMAKE_BUILD_TYPE=Release
+
+# 设置目标操作系统
 set(CMAKE_SYSTEM_NAME Linux)
 
-#set(CMAKE_SYSTEM_PROCESSOR mips32)
-#set(CMAKE_SYSTEM_PROCESSOR arm64)
+# 也可以在这里设置处理器架构
+# 一般有 armv7-a|aarch64|mips|arm64|riscv64|riscv32 等值
+# set(CMAKE_SYSTEM_PROCESSOR aarch64)
 
-# see https://toolchains.bootlin.com/
-# which compilers to use for C and C++
+# 设置编译器名称，必须在 PATH 中，一般名称比如：
 # mipsel-linux-g++
 # mipsel-openwrt-linux-musl-gcc
-# ...
 
 set(CMAKE_C_COMPILER   ${COMPILER}-gcc)
 set(CMAKE_CXX_COMPILER ${COMPILER}-g++)
 
-# where is the target environment located
 #set(CMAKE_FIND_ROOT_PATH /usr/bin)
-
-# adjust the default behavior of the FIND_XXX() commands:
-# 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)