Getting started with CMake, examples and templates

What is CMake

CMake allows developers to write a platform-independent CMakeList.txt file to customize the entire compilation process, and then further generate the required localized Makefile and project files according to the target user’s platform, such as Unix Makefile or Windows Visual Studio project. Thus achieving “Write once, run everywhere”.

The process of using CMake to generate Makefile and compile under Linux platform is as follows:

Write the CMake configuration file CMakeLists.txt.
Execute the command cmake PATH or ccmake PATH to generate Makefile (the difference between ccmake and cmake is that the former provides an interactive interface). Among them, PATH is the directory where CMakeLists.txt is located.

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# 一般是创建一个build目录进行编译，CMakeLists.txt在build目录的上一层
mkdir ./build
cd build
cmake ..
make

Use the make command to compile.

Template 1 single source file

It is suitable for compiling the specified source file (test01.cpp) in a certain directory without calling a third-party library, and finally compiling it into an executable file.

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# 1,设置工程名称，叫“Demo1”，在Linux下可以随便设置
project( Demo1 )

# 2,设置 CMake 最低版本号，我电脑装的是3.5
cmake_minimum_required( VERSION 3.5 )

# 3,设定编译参数
set(CMAKE_CXX_STANDARD    11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE "Release")  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

# 4，把源码编译成一个可执行文件，文件名为test01（可以随便取名），会保存在当前目录下
add_executable( test01 test01.cpp )

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├── template1
│    ├── CMakeLists.txt
│    └── test02.cpp

Running process

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cd template1
mkdir ./build
cd build
cmake ..
make

The executable file test01 will be generated in the build directory.

Template 2 Multiple source files in one directory

It is suitable for compiling multiple source files in the same directory without calling third-party libraries, and finally compiling them into an executable file. Source files .c .cpp .cc and include files are all placed in one directory. There is only one directory and no subdirectories.

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# 1,设置工程名称，叫“Demo2”（在Linux下可以随便设置）
project( Demo2 )

# 2,设置 CMake 最低版本号，我电脑装的是3.5
cmake_minimum_required( VERSION 3.5 )

# 3,设定编译参数
set(CMAKE_CXX_STANDARD    11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE "Release")  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

# 4，把当前文件夹下的源码列表（文件后缀匹配的那些文件）存到变量 SRCS 中
file( GLOB SRCS *.c *.cpp *.cc *.h *.hpp )

# 5，把源码编译成一个可执行文件，文件名为test02（可以随便取名），会保存在当前目录下
add_executable( test02 ${SRCS} )

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├── template2
│    ├── CMakeLists.txt
│    ├── test02.cpp
│    └── test02.h

There can be more source files and include files, as long as they are placed in one directory

Running process

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cd template2
mkdir ./build
cd build
cmake ..
make

The executable file test02 will be generated in the build directory.

Template 3 source files and include files are in different directories

It is suitable for situations where the cpp file is in one folder (src/), the header file is in another folder (include/), and no third-party library is called, and is finally compiled into an executable file.

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# 1,设置工程名称，叫“Demo3”，在Linux下可以随便设置
project( Demo3 )

# 2,设置 CMake 最低版本号，我电脑装的是3.5
cmake_minimum_required( VERSION 3.5 )

# 3,设定编译参数
set(CMAKE_CXX_STANDARD    11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE "Release")  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

# 4,设定源码列表,查找指定目录下的所有源文件,并将名称保存到 DIR_SRCS 变量中
aux_source_directory(./src/ DIR_SRC)

# 5,设定头文件路径
include_directories(./include/)

# 6，把源码编译成一个可执行文件，文件名为test03（可以随便取名），会保存在当前目录下
add_executable( test03 ${DIR_SRC} )

Directory structure

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├── template3
│   ├── CMakeLists.txt
│   ├── include
│   │   └── count.h
│   └── src
│       ├── count.cpp
│       └── test03.cpp

Running process

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cd template3
mkdir ./build
cd build
cmake ..
make

The executable file test03 will be generated in the build directory.

Template 4 source files and include files are in different directories, calling third-party libraries installed in the system

It is suitable for situations where the cpp file is in one folder (src/), the header file is in another folder (include/), and a third-party library (such as opencv already installed in the system) is called, and finally compiled into an executable file.

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# 1,设置工程名称，叫“Demo4”，在Linux下可以随便设置
project( Demo4 )

# 2,设置 CMake 最低版本号，我电脑装的是3.5
cmake_minimum_required( VERSION 3.5 )

# 3,设定编译参数
set(CMAKE_CXX_STANDARD    11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE "Release")  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

# 4,设定源码列表,查找指定目录(都放在./src/中)中的所有源文件,并将名称保存到 DIR_SRCS 变量中
aux_source_directory(./src/ DIR_SRC)

# 5,设定头文件路径（还可以增加其他第三方库的头文件路径）
include_directories(./include/)

# 6,查找并添加OpenCV的头文件目录
find_package(OpenCV REQUIRED)  
# message( STATUS "    version: ${OpenCV_VERSION}" )  # 我电脑上装的是opencv3.3.1
# message( STATUS "    include path: ${OpenCV_INCLUDE_DIRS}" )
include_directories(${OpenCV_INCLUDE_DIRS})

# 7，把源码编译成一个可执行文件，文件名为test04（可以随便取名），会保存在当前目录下
add_executable( test04 ${DIR_SRC} )
target_link_libraries( test04 ${OpenCV_LIBS} )  # 可执行文件名 链接 OpenCV库

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├── template4
│   ├── CMakeLists.txt
│   ├── include
│   │   └── test04.h
│   └── src
│       └── test04.cpp

Running process

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## 要先安装 opencv ubuntu下
sudo apt install libopencv-dev
cd template4
mkdir ./build
cd build
cmake ..
make

The executable file test04 will be generated in the build directory.

Template 5 is divided into multiple sub-modules. Each sub-module has its own CMakeLists.txt, which generates executable files, static libraries, and dynamic libraries.

Use cmake to build a project. Each submodule has its own cmakelists. The project creates two static libraries and a dynamic library, and also generates an executable file that calls these libraries. CMakeLists.txt

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cmake_minimum_required(VERSION 3.5)  # cmake版本最低要求
project(test5)  # 设置工程名称

set(CMAKE_CXX_STANDARD 11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE Release)  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

message("${PROJECT_SOURCE_DIR}=" ${PROJECT_SOURCE_DIR})

# 这里设置好路径后，进入子模块的cmake时不用再次设置
SET(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)  # 设置可执行文件的输出目录
SET(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib)	   # 设置库文件的输出目录

ADD_SUBDIRECTORY(${PROJECT_SOURCE_DIR}/source/add)     # 会调用该目录中的CMakeLists.txt进行编译生成静态库
ADD_SUBDIRECTORY(${PROJECT_SOURCE_DIR}/source/sub)     # 会调用该目录中的CMakeLists.txt进行编译生成静态库
ADD_SUBDIRECTORY(${PROJECT_SOURCE_DIR}/source/mul)     # 会调用该目录中的CMakeLists.txt进行编译生成动态库
ADD_SUBDIRECTORY(${PROJECT_SOURCE_DIR}/source/main)    # 会调用该目录中的CMakeLists.txt进行编译生成可执行文件

add/CMakeLists.txt

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# 编译成静态库, libadd.a
# 方法一：逐个添加cpp源文件，适用于文件数量少的情况
# add_library(add ${CMAKE_CURRENT_SOURCE_DIR}/add.cpp ${CMAKE_CURRENT_SOURCE_DIR}/add3.cpp)

# 方法二：搜索有的cpp源文件，并将列表存储在一个变量中，适用于文件多的情况
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} SRC_LIST)
add_library(add ${SRC_LIST})

# 方法三：递归遍历目录，获取所有的CPP文件，适用于多级目录的情况
# file(GLOB_RECURSE cpp_files  ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp)  # GLOB是不递归
# add_library(add ${cpp_files})

mul/CMakeLists.txt

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# 编译成动态库libmul.so
add_library(mul SHARED ${CMAKE_CURRENT_SOURCE_DIR}/mul.cpp)

sub/CMakeLists.txt

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# 编译成静态库, libsub.a
add_library(sub ${CMAKE_CURRENT_SOURCE_DIR}/sub.cpp)

main/CMakeLists.txt

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# 添加头文件路径，会检索目录中的所有头文件
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/../add
                    ${CMAKE_CURRENT_SOURCE_DIR}/../sub
                    ${CMAKE_CURRENT_SOURCE_DIR}/../mul
                    ${CMAKE_CURRENT_SOURCE_DIR}/../main)

# 把源码编译成一个可执行文件
add_executable(main ./main.cpp)
# 添加链接库，动态和静态都行
target_link_libraries(main add sub mul)

Directory structure

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├── template5
│   ├── CMakeLists.txt
│   ├── readme.md
│   ├── run.sh
│   └── source
│       ├── add
│       │   ├── add3.cpp
│       │   ├── add3.h
│       │   ├── add.cpp
│       │   ├── add.h
│       │   └── CMakeLists.txt
│       ├── main
│       │   ├── CMakeLists.txt
│       │   └── main.cpp
│       ├── mul
│       │   ├── CMakeLists.txt
│       │   ├── mul.cpp
│       │   └── mul.h
│       └── sub
│           ├── CMakeLists.txt
│           ├── sub.cpp
│           └── sub.h

Running process

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cd template5
rm -rf build
mkdir build
cd build/
cmake ..
make  
cd ../bin
./main

Template 6 is divided into multiple sub-modules, with only one CMakeLists.txt, which generates executable files, static libraries, and dynamic libraries.

Use cmake to build a project that contains multiple submodules, but the submodules do not have their own cmakelists. The entire project has only one CMakeLists.txt. The project creates two static libraries and a dynamic library, and also generates an executable file that calls these libraries.

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cmake_minimum_required(VERSION 3.5)  # cmake版本最低要求
project(test6)  # 设置工程名称

set(CMAKE_CXX_STANDARD 11)  # 指定 C++ 版本
set(CMAKE_BUILD_TYPE Release)  # 调试使用Debug，可以查看中间变量；发布使用Release，运行速度快

message("${PROJECT_SOURCE_DIR}=" ${PROJECT_SOURCE_DIR})

# 这里设置好路径后，进入子模块的cmake时不用再次设置
SET(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)  # 设置可执行文件的输出目录
SET(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib)	   # 设置库文件的输出目录

# 编译add，生成静态库
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/source/add ADD_SRC_LIST)
add_library(add ${ADD_SRC_LIST})

# 编译sub，生成静态库
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/source/sub SUB_SRC_LIST)
add_library(sub ${SUB_SRC_LIST})

# 编译mul，生成动态库
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/source/mul MUL_SRC_LIST)
add_library(mul SHARED ${MUL_SRC_LIST})

# 添加头文件路径，用于编译可执行文件
include_directories(./source/add
                    ./source/sub
                    ./source/mul)

# 编译main，生成可执行文件
add_executable(main ${CMAKE_CURRENT_SOURCE_DIR}/source/main/main.cpp)
target_link_libraries(main add sub mul)  # 链接所有库

Directory structure

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├── template6
│   ├── CMakeLists.txt
│   ├── readme.md
│   ├── run.sh
│   └── source
│       ├── add
│       │   ├── add3.cpp
│       │   ├── add3.h
│       │   ├── add.cpp
│       │   └── add.h
│       ├── main
│       │   └── main.cpp
│       ├── mul
│       │   ├── mul.cpp
│       │   └── mul.h
│       └── sub
│           ├── sub.cpp
│           └── sub.h

Running process

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cd template6
rm -rf build
mkdir build
cd build/
cmake ..
make 
cd ../bin
./main

Common commands

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# Note：cmake中不区分大小写。

# 设置变量，方便后面自动配置，进入子模块的cmake时不用再次设置
SET(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)  # 设置可执行文件的输出目录
SET(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib)	   # 设置库文件的输出目录

# 设定源码列表,查找指定目录下的所有源文件,并将名称保存到 DIR_SRCS 变量中
aux_source_directory(./src/ DIR_SRC)

# 设定头文件查找路径，可以将所有头文件路径都添加到这里面
include_directories(./include/
                    ./source/sub)

# 查找并添加OpenCV的头文件目录，在target_link_libraries()中需要进行动态链接
find_package(OpenCV REQUIRED) 

# 编译子模块，会自动调用子模块中的Cmakelists.txt进行编译
add_subdirectory(sub)

# 将${ADD_SRC_LIST}中的所有源码编译生成静态库add
add_library(add ${ADD_SRC_LIST})

# 将${SRCS}中的所有源码编译成一个可执行文件，文件名为main
add_executable( main ${SRCS} )
# 编译可执行文件之后，添加动态链接库，会链接静态库subadd和opencv库
target_link_libraries(main subadd ${OpenCV_LIBS})

# 打印一些日志信息
message("PROJECT_SOURCE_DIR=" ${PROJECT_SOURCE_DIR})

Commonly used variables

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# Note：cmake中不区分大小写。

# 工程顶层目录
${CMAKE_SOURCE_DIR} ${PROJECT_SOURCE_DIR}

# 当前处理的 CMakeLists.txt 所在路径
${CMAKE_CURRENT_SOURCE_DIR}

# 返回Cmakelists.txt开头通过 PROJECT 指令定义的项目名称
${PROJECT_NAME}

# 分别用来重新定义最终结果（可执行文件、动静态库文件）的存放目录
${EXECUTABLE_OUTPUT_PATH} ${LIBRARY_OUTPUT_PATH}

Additional 1 Cross Compilation CH32V203

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set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_VERSION 1)
set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
cmake_minimum_required(VERSION 3.20)

# 工具链设置
set(TOOLPATH  D:/0wch/toolchain/RISCVEmbeddedGCC/bin/riscv-none-embed-)

if (WIN32)
	MESSAGE(STATUS "Now is windows!")
    set(CMAKE_C_COMPILER ${TOOLPATH}gcc.exe)
    set(CMAKE_CXX_COMPILER ${TOOLPATH}g++.exe)
    set(CMAKE_ASM_COMPILER ${TOOLPATH}gcc.exe)
    set(CMAKE_AR ${TOOLPATH}ar.exe)
    set(CMAKE_OBJCOPY ${TOOLPATH}objcopy.exe)
    set(CMAKE_OBJDUMP ${TOOLPATH}objdump.exe)
    set(SIZE ${TOOLPATH}size.exe)
elseif (UNIX)
	MESSAGE(STATUS "Now is UNIX-like OS!")
    set(CMAKE_C_COMPILER ${TOOLPATH}gcc)
    set(CMAKE_CXX_COMPILER ${TOOLPATH}g++)
    set(CMAKE_ASM_COMPILER ${TOOLPATH}gcc)
    set(CMAKE_AR ${TOOLPATH}ar)
    set(CMAKE_OBJCOPY ${TOOLPATH}objcopy)
    set(CMAKE_OBJDUMP ${TOOLPATH}objdump)
    set(SIZE ${TOOLPATH}size)
else ()
    MESSAGE(STATUS "Unsupported system!")
endif ()

# 项目设置
project(ch32v203-ninja C CXX ASM)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_C_STANDARD 99)

# 编译参数 一般不用改
add_compile_options(-march=rv32imac -mabi=ilp32 -mcmodel=medany -msmall-data-limit=8 -mno-save-restore)
add_compile_options(-fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-common)

# 编译等级
add_compile_options(-O2)

# 编译信息等级
add_compile_options(-Wall)

# 头文件路径
include_directories(APP
                    Core
                    Debug 
                    Peripheral/inc)

# 宏定义
# add_definitions(-DDEBUG=1)

# 源码文件
file(GLOB_RECURSE SOURCES 
                "APP/*.c"
                "Core/core_riscv.c" 
                "Debug/debug.c"
                "Peripheral/src/*.c" 
                "Startup/startup_ch32v20x_D6.S"
                )

# 链接参数
set(LINKER_SCRIPT  ${CMAKE_SOURCE_DIR}/Ld/Link.ld)
add_link_options(
                -march=rv32imac -mabi=ilp32
                -nostartfiles 
                -Xlinker --gc-sections  
                -Wl,--print-memory-usage
                -Wl,-Map,${PROJECT_NAME}.map 
                --specs=nano.specs 
                --specs=nosys.specs)
add_link_options(-T ${LINKER_SCRIPT})

# 编译可执行文件
add_executable(${PROJECT_NAME}.elf ${SOURCES} ${LINKER_SCRIPT})

# 链接静态库
# target_link_libraries(${PROJECT_NAME}.elf printfloat)

# 输出hex和bin
set(HEX_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.hex)
set(BIN_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.bin)
set(LST_FILE ${PROJECT_BINARY_DIR}/${PROJECT_NAME}.lst)
add_custom_command(TARGET ${PROJECT_NAME}.elf POST_BUILD
        COMMAND ${CMAKE_OBJCOPY} -Oihex $<TARGET_FILE:${PROJECT_NAME}.elf> ${HEX_FILE}
        COMMAND ${CMAKE_OBJCOPY} -Obinary $<TARGET_FILE:${PROJECT_NAME}.elf> ${BIN_FILE}
        COMMAND ${CMAKE_OBJDUMP} --all-headers --demangle --disassemble $<TARGET_FILE:${PROJECT_NAME}.elf> > ${LST_FILE}
        COMMAND ${SIZE} --format=berkeley $<TARGET_FILE:${PROJECT_NAME}.elf>
)

Link.ld file

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ENTRY( _start )

__stack_size = 2048;

PROVIDE( _stack_size = __stack_size );


MEMORY
{  
/* CH32V20x_D6 - CH32V203F6-CH32V203G6-CH32V203K6-CH32V203C6 */
	FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 32K
	RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 10K

/* CH32V20x_D6 - CH32V203K8-CH32V203C8-CH32V203G8-CH32V203F8 */
	/* FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 64K
	RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 20K */
 
/* CH32V20x_D8 - CH32V203RB
   CH32V20x_D8W - CH32V208x
   FLASH + RAM supports the following configuration
   FLASH-128K + RAM-64K
   FLASH-144K + RAM-48K
   FLASH-160K + RAM-32K

	FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 160K
	RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 32K
*/
}


SECTIONS
{

	.init :
	{
		_sinit = .;
		. = ALIGN(4);
		KEEP(*(SORT_NONE(.init)))
		. = ALIGN(4);
		_einit = .;
	} >FLASH AT>FLASH

  .vector :
  {
      *(.vector);
	  . = ALIGN(64);
  } >FLASH AT>FLASH

	.text :
	{
		. = ALIGN(4);
		*(.text)
		*(.text.*)
		*(.rodata)
		*(.rodata*)
		*(.glue_7)
		*(.glue_7t)
		*(.gnu.linkonce.t.*)
		. = ALIGN(4);
	} >FLASH AT>FLASH 

	.fini :
	{
		KEEP(*(SORT_NONE(.fini)))
		. = ALIGN(4);
	} >FLASH AT>FLASH

	PROVIDE( _etext = . );
	PROVIDE( _eitcm = . );	

	.preinit_array  :
	{
	  PROVIDE_HIDDEN (__preinit_array_start = .);
	  KEEP (*(.preinit_array))
	  PROVIDE_HIDDEN (__preinit_array_end = .);
	} >FLASH AT>FLASH 
	
	.init_array     :
	{
	  PROVIDE_HIDDEN (__init_array_start = .);
	  KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
	  KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
	  PROVIDE_HIDDEN (__init_array_end = .);
	} >FLASH AT>FLASH 
	
	.fini_array     :
	{
	  PROVIDE_HIDDEN (__fini_array_start = .);
	  KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
	  KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
	  PROVIDE_HIDDEN (__fini_array_end = .);
	} >FLASH AT>FLASH 
	
	.ctors          :
	{
	  /* gcc uses crtbegin.o to find the start of
	     the constructors, so we make sure it is
	     first.  Because this is a wildcard, it
	     doesn't matter if the user does not
	     actually link against crtbegin.o; the
	     linker won't look for a file to match a
	     wildcard.  The wildcard also means that it
	     doesn't matter which directory crtbegin.o
	     is in.  */
	  KEEP (*crtbegin.o(.ctors))
	  KEEP (*crtbegin?.o(.ctors))
	  /* We don't want to include the .ctor section from
	     the crtend.o file until after the sorted ctors.
	     The .ctor section from the crtend file contains the
	     end of ctors marker and it must be last */
	  KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
	  KEEP (*(SORT(.ctors.*)))
	  KEEP (*(.ctors))
	} >FLASH AT>FLASH 
	
	.dtors          :
	{
	  KEEP (*crtbegin.o(.dtors))
	  KEEP (*crtbegin?.o(.dtors))
	  KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
	  KEEP (*(SORT(.dtors.*)))
	  KEEP (*(.dtors))
	} >FLASH AT>FLASH 

	.dalign :
	{
		. = ALIGN(4);
		PROVIDE(_data_vma = .);
	} >RAM AT>FLASH	

	.dlalign :
	{
		. = ALIGN(4); 
		PROVIDE(_data_lma = .);
	} >FLASH AT>FLASH

	.data :
	{
    	*(.gnu.linkonce.r.*)
    	*(.data .data.*)
    	*(.gnu.linkonce.d.*)
		. = ALIGN(8);
    	PROVIDE( __global_pointer$ = . + 0x800 );
    	*(.sdata .sdata.*)
		*(.sdata2.*)
    	*(.gnu.linkonce.s.*)
    	. = ALIGN(8);
    	*(.srodata.cst16)
    	*(.srodata.cst8)
    	*(.srodata.cst4)
    	*(.srodata.cst2)
    	*(.srodata .srodata.*)
    	. = ALIGN(4);
		PROVIDE( _edata = .);
	} >RAM AT>FLASH

	.bss :
	{
		. = ALIGN(4);
		PROVIDE( _sbss = .);
  	    *(.sbss*)
        *(.gnu.linkonce.sb.*)
		*(.bss*)
     	*(.gnu.linkonce.b.*)		
		*(COMMON*)
		. = ALIGN(4);
		PROVIDE( _ebss = .);
	} >RAM AT>FLASH

	PROVIDE( _end = _ebss);
	PROVIDE( end = . );

    .stack ORIGIN(RAM) + LENGTH(RAM) - __stack_size :
    {
        PROVIDE( _heap_end = . );   
        . = ALIGN(4);
        PROVIDE(_susrstack = . );
        . = . + __stack_size;
        PROVIDE( _eusrstack = .);
    } >RAM 

}