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OpenAMP MicroBlaze example

The microblaze_generic directories in OpenAMP repository provide an implementation of rpmsg for Xilinx MicroBlaze design example. The design instantiates Xilinx MicroBlaze soft processor in ZynqMP’s programmable logic (PL) and uses the processing system (PS) DDR memory for its text and data. The HP0_DDR_LOW is mapped from 0 to 0x7FFFFFFF. The Local Memory Bus (LMB) is not connected and the LMB memory is not present. The MicroBlaze Vector Base Address is set to 0x70000000 and its reset_mode (01) will force it to enter sleep mode without performing any bus access. The design is available in the Xilinx Shell Archive (XSA) format at https://xilinx-wiki.atlassian.net

How to build OpenAMP echo server for the MicroBlaze design example.

For simplicity the example is not using Inter-Processor Interrupt (IPI) hardware at this time and the MicroBlaze OpenAMP echo server is built with RPMSG_NO_IPI flag.

build the libmetal library on your host as follows:

Create your own cmake toolchain file to compile libmetal for your generic (baremetal) platform. Here is an example toolchain file:

    set (BSP  "/path/to/your_MicroBlaze_design_BSP/dir" CACHE STRING "")
    set (CMAKE_SYSTEM_PROCESSOR           "microblaze"  CACHE STRING "")
    set (MACHINE           "microblaze_generic"         CACHE STRING "")
    set (CROSS_PREFIX          "microblaze-xilinx-elf-" CACHE STRING "")
    set (CMAKE_C_FLAGS "-g -mlittle-endian -mxl-soft-mul -Wall -Werror \
                   "-Wextra -flto -Os -I${BSP}/include" CACHE STRING "")
    link_directories( ${BSP}/lib )
    SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -flto")
    SET(CMAKE_AR  "gcc-ar" CACHE STRING "")
    SET(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> qcs <TARGET> <LINK_FLAGS> <OBJECTS>")
    SET(CMAKE_C_ARCHIVE_FINISH   true)
    include (cross-generic-gcc)

Compile the libmetal library:

    $ mkdir -p build-libmetal
    $ cd build-libmetal
    $ BSP="/path/to/your_MicroBlaze_design_BSP/dir"
    $ cmake <libmetal_source> -DCMAKE_TOOLCHAIN_FILE=<toolchain_file> \
            -DCMAKE_LIBRARY_PATH=$BSP/lib
    $ make VERBOSE=1 DESTDIR=<libmetal_install> install

build the OpenAMP library on your host as follows:

Create your own cmake toolchain file to compile openamp for your generic (baremetal) platform. Here is an example toolchain file:

    set (BSP  "/path/to/your_MicroBlaze_design_BSP/dir" CACHE STRING "")
    set (CMAKE_SYSTEM_PROCESSOR           "microblaze"  CACHE STRING "")
    set (MACHINE           "microblaze_generic"         CACHE STRING "")
    set (CROSS_PREFIX          "microblaze-xilinx-elf-" CACHE STRING "")
    set (CMAKE_C_FLAGS "-g -mlittle-endian -Wall -Wextra -flto -Os \
            -DUNDEFINE_FILE_OPS -DRPMSG_NO_IPI -I${LIBMETAL}/include \
            -I${BSP}/include" CACHE STRING "")

    set (PLATFORM_LIB_DEPS     "-lxil -lc -lm -lmetal " CACHE STRING "")
    SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -flto")
    SET(CMAKE_AR  "gcc-ar" CACHE STRING "")
    SET(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> qcs <TARGET> <LINK_FLAGS> <OBJECTS>")
    SET(CMAKE_C_ARCHIVE_FINISH   true)
    link_directories(${LIBMETAL}/include/ ${LIBMETAL}/lib/)
    set (CMAKE_FIND_ROOT_PATH ${LIBMETAL}/lib  ${BSP}/lib )
    include (cross-generic-gcc)

We use cmake find_path and find_library to check if libmetal headers and library are in the includes and library search paths. However, for non-linux system, it doesn’t work with CMAKE_INCLUDE_PATH and CMAKE_LIBRARY_PATH variables, and thus, we need to specify those paths in the toolchain file with CMAKE_C_FLAGS and CMAKE_FIND_ROOT_PATH.

Compile the OpenAMP library:

$ mkdir -p build-openamp
$ cd build-openamp
$ BSP="/path/to/your_MicroBlaze_design_BSP/dir"

$ cmake <openamp_source> -DCMAKE_TOOLCHAIN_FILE=<toolchain_file> \
    -DCMAKE_INCLUDE_PATH="$LIBMETAL/include;$BSP/include" \
    -DCMAKE_LIBRARY_PATH="$LIBMETAL/lib/;BSP/lib"  -DWITH_APPS=on
$ make VERBOSE=1 DESTDIR=$(pwd) install

The OpenAMP library will be built in build/usr/local/lib directory, headers will be built in build/usr/local/include directory, and the application executable will be built in build/usr/local/bin directory.

How to build OpenAMP Linux Userspace echo Client for ZynqMP MPSoC

To test the MicroBlaze echo server we use an rpmsg-echo-ping client from Linux running on the Application Processing Unit (APU) in PS. To run both the echo server on the MicroBlaze in PL from PS DDR and a Linux echo client on APU in PS the kernel device tree needs reserved-memory nodes for the MicroBlaze text and data including vrings. A Yocto overlay device tree example: openamp-linux-u-MicroBlaze.dtsi

Build the OpenAMP Linux userspace library and application via Yocto. The open-amp and libmetal recipes are in this Yocto layer: https://github.com/OpenAMP/meta-openamp

Add the meta-openamp layer to your layers in your Yocto build project’s bblayers.conf file.
Add libmetal and open-amp to your packages list. E.g. add libmetal and open-amp to the IMAGE_INSTALL_append in the local.conf file.
You can also add OpenAMP demos Linux applications packages to your Yocto packages list. OpenAMP demo examples recipes are also in meta-openamp: https://github.com/OpenAMP/meta-openamp/tree/master/recipes-openamp/openamp-examples

Sample Microblaze DTSI

/ {
	reserved-memory {
		#address-cells = <2>;
		#size-cells = <2>;
		ranges;
		rproc_0_reserved: rproc@3ed000000 {
			no-map;
			reg = <0x0 0x3ed00000 0x0 0x1000000>;
		};
		microblaze_text_data: microblaze:@70000000 {
			no-map;
			reg = <0x0 0x70000000 0x0 0x80000>;
		};
	};

	amba {
		vring: vring@0 {
			compatible = "vring_uio";
			reg = <0x0 0x3ed40000 0x0 0x40000>;
		};
		shm0: shm@0 {
			compatible = "shm_uio";
			reg = <0x0 0x3ed20000 0x0 0x0100000>;
		};
		shm1: shm@1 {
			compatible = "shm_uio";
			reg = <0x0 0x3ee40000 0x0 0x0100000>;
		};
		ipi0: ipi@0 {
			compatible = "ipi_uio";
			reg = <0x0 0xff340000 0x0 0x1000>;
			interrupt-parent = <&gic>;
			interrupts = <0 29 4>;
		};
	};
};