250 lines
9.3 KiB
Plaintext
250 lines
9.3 KiB
Plaintext
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=========================================================
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Getting started with Genode on MicroBlaze based platforms
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=========================================================
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Martin Stein
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This file describes in a practical manner how to work with Genode on platforms
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which are based on the Xilinx MicroBlaze. It approaches the following aspects:
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* Build Genode with an existing static scenario of programs which are interacting
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on with each other and printing information about it to the serial port.
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* Run this Genode scenario on Qemu and on the Xilinx Spartan 3A Starter Kit
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* Implement basic support aspects for new MicroBlaze-based platforms
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If you're not familar with the Genode OS framework, you can read the online
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documentation:
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[http://genode.org/documentation/]
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If you need further information about the Xilinx MicroBlaze, you can read an
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introduction written by the Genode developers inside your Genode directory:
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'base-mb/doc/microblaze.txt'
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It also covers general issues and limitations respecting the status quo of the
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Genode porting for MicroBlaze-based platforms. To go in detail about the Xilinx
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MicroBlaze, you may refer to the Xilinx documentation:
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[http://www.xilinx.com/tools/microblaze.htm]
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Prerequisites
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=============
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The MicroBlaze tool chain
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~~~~~~~~~~~~~~~~~~~~~~~~~
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To build Genode for MicroBlaze, it is recommended to use the following
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GCC/binutils-compliant tools:
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* mb-g++ (GCC) 4.1.1 20060524 (Xilinx 11.2 Build EDK_LS2.2 20 Apr 2009 Xilinx
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11.2 Build EDK_LS2.2 23 Apr 2009)
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* GNU ld version 2.16 Xilinx 11.2 Build EDK_LS2.2 23 Apr 2009
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* GNU assembler 2.16 Xilinx 11.2 Build EDK_LS2.2 23 Apr 2009
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These tools come with the Xilinx Embedded Development Kit (EDK).
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Expect
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~~~~~~
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To run the given test scenarios on Genode, you have to install the Tcl-based
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testing-tool Expect, for example using 'apt-get' on Debian-based Linux
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distributions:
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! sudo apt-get install expect
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Qemu
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~~~~
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To run Genode's MicroBlaze port on Qemu, the following Qemu-version is recommended:
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QEMU emulator version 0.14.50, Copyright (c) 2003-2008 Fabrice Bellard
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You can get the source code of the latest version via GIT as follows:
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! git clone git://git.qemu.org/qemu.git
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For the scenarios described in here, you have to compile qemu via:
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! configure --target-list=microblaze-softmmu
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! make
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Hardware
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~~~~~~~~
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The tutorial that runs Genode on hardware uses the Xilinx Spartan 3A Starter Kit
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Revision D board with the FPGA 'xc3s700a', package 'fg484' on speed grade '-4'.
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It has to be connected to your machine via USB and a serial port RS-232.
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Tutorial: Build and run Genode's MicroBlaze port
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================================================
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Initially go to your Genode directory and ensure that the value of the 'QEMU' variable
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within 'tool/builddir/etc/build.conf.mb-s3a_starter_kit' conforms to the path
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of your 'qemu-system-microblaze' command. Now build a build directory with the
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following shell commands:
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! ./tool/create_builddir mb-s3a_starter_kit \
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! BUILD_DIR=build.mb-s3a_starter_kit \
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On Qemu
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~~~~~~~
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Change to '<GENODE_DIR>/build.mb-s3a_starter_kit'. In this directory,
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build and run the Genode scenario 'nested_init' for Qemu as follows:
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! make run/nested_init
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This instructs the Genode build system to act according to the run-script
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'<GENODE_DIR>/base-mb/run/nested_init.run'. This script initiates the build of
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the Genode's core, the program 'init', and a configuration that describes the
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scenario init start. Then it constructs a bootable image of these 3 files and
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finally starts Qemu to boot the image virtually. Genode then starts 2 nested
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'init' programs, each 'init' instance prints some information about its
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capabilities.
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On Hardware
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~~~~~~~~~~~
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Ensure that the Xilinx Spartan 3A Starter Kit jumpers are set as described for
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the board-intern demo. Connect the board via USB to your machine and turn it
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on. Wait till the LED next to the USB connector on board lights up, then list
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all connected USB devices:
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! lsusb
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This should print, among others, one line like this 'Bus XXX Device XXX: ID XXXX:0008
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Xilinx, Inc.' (any X is a wildcard for a number 0-9). Now connect the Serial port that
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is labeled on board with 'J27' with your computer, this allows us to track debugging
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output from Genode later. Go to '<GENODE_DIR>/build.mb-s3a_starter_kit'.
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First we have to configure the Spartan 3A with an appropriate MicroBlaze SoC as follows:
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! make -C ../base-mb/platform/mb-s3a_starter_kit
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If it has finished successfully, we can build and run the 'nested_init' scenario by
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typing the following command from within the build directory:
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! RUN_OPT="--target jtag" make run/nested_init
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After this, the build chain leaves an XMD command prompt to you, which is connected
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to the SoC on the FPGA via JTAG, so you can steer it as you wish. Genode isn't started
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already, you can now run a program like 'gtkterm' which intercepts the serial port that
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Genode will print to. The parameters of the serial port according to 'gtkterm' are:
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* Speed = 9600
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* Parity = none
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* Bits = 8
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* Stopbits = 1
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* Flowcontrol = none
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To start the execution of the 'nested_init' scenario type
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! run
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to the open XMD prompt. The serial port interception should show output similar
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to that of the Qemu-run. You should avoid uploading multiple times to a once
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configured platform, it can lead to memory inconsistency. In contrast when
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configuring the FPGA in between the RAM gets reset.
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Other scenarios
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~~~~~~~~~~~~~~~
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You can also find a simple hello-world program at 'base-mb/src/test/hello'.
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An appropriate 'run' script also exists and can be build from within a build
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directory via:
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! RUN_OPT="--target <TARGET>" make run/hello
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Hints: How to add support for other MicroBlaze-based platforms
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==============================================================
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The steps described in here don't claim to be complete. They solely should
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cover the basic of aspects to be considered when implementing support for new
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platforms and reflect main conventions Genode's MicroBlaze port relies to.
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New MicroBlaze-based platforms have to fulfill several considerations for now
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to be compliant to the Genode port. The core expects:
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* A MicroBlaze SoC with software-loaded MMU that has 64 entries,
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RAM accessibility and no instruction- and data- caches
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* The RAM address space to be mapped to 0x90000000
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* The CPUs IRQ controller to be an XPS interrupt controller,
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mapped to 0x81800000
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* An XPS Timer mapped to 0x83c00000 with IRQ 0
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* An XPS UART Lite mapped to 0x84000000
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Basics
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~~~~~~
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Add a file 'base-mb/mk/spec-<PLATFORM>.mk' with the content
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! SPECS += <SPECS>
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! STARTUP_LIB ?= startup
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! PRG_LIBS += $(STARTUP_LIB)
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This file contains aspects to be integrated if 'PLATFORM' occurs in the
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make-variable 'SPECS' during the build process. It also can add 'SPECS' by
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itself to provide further details to the build system. For example,
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the word-width of the CPU like '32bit'. Any other program or library
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can depend on 'PLATFORM' later by adding it to its 'SPECS'. The second and third
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lines specify a library that all userland-programs on Genode use to start on
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'PLATFORM'. The denoted one is the default '<GENODE_DIR>/base-mb/lib/mk/startup.mk'
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used by the currently supported platforms.
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You can influence the build-process for 'PLATFORM' furthermore by adding additional
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lines to this file, for according documentation please refer to:
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[http://genode.org/documentation/]
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FPGA Configuration and support by the tool 'run'
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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To automate testing via the 'run' tool, you have to create a Makefile
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'<GENODE_DIR>/base-mb/platform/<PLATFORM>/Makefile' that provides a target
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'upload'. This target should upload an ELF-image, whose absolute path is
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given by the make argument 'IMAGE', to the according hardware.
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The above mentioned Makefile should also provide by convention a target
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'configure' which prepares the according hardware for the upload of
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boot images. Typically it configures the FPGA with an appropriate
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SoC. Therefore, whose source should also be located within
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'<GENODE_DIR>/base-mb/platform/<PLATFORM>/'.
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Finally you have to edit '<GENODE_DIR>/base-mb/run/env' to hint 'run' to
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your platform. Add inside the function definition 'proc hardware { } {'
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an additional:
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! if { [have_spec {<PLATFORM>}] } {
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! set _hardware <PLATFORM>
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! return $_hardware
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! }
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'run' then calls 'upload' on '<GENODE_DIR>/base-mb/platform/<PLATFORM>/Makefile'
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and gives the boot image when 'run_genode_until' is called by the according
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'run'-script. But first you should create an according build directory as described
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next.
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Support for the tool 'create_builddir'
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Add a file 'tool/builddir/etc/build.conf.<PLATFORM>' with at least the content
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! REPOSITORIES = base-mb
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! QEMU = <QEMU>
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Where 'QEMU' denotes your Qemu command to emulate 'PLATFORM' for Genode
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Now add a make-target '<PLATFORM>::' to 'tool/create_builddir' that should
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describe additional things to do for your build directory. A good point to
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start is to overwrite the default specifications the build process should take
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into account when selecting and build targets and libraries.
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! @echo "SPECS = genode <PLATFORM>" > $(BUILD_DIR)/etc/specs.conf
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This adds the specifics for basic Genode settings, libraries and programs as
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well as to the contents of your previously created
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'base-mb/mk/spec-<PLATFORM>.mk'.
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