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138 lines
4.6 KiB
Plaintext
138 lines
4.6 KiB
Plaintext
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==============================
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Genode on the OKL4 microkernel
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==============================
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Stefan Kalkowski
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OKl4 is a microkernel developed and distributed by Open Kernel Labs. It is
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focused on embedded devices. Genode support the OKL4 kernel version 2.1
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on the x86_32 platform.
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This document provides brief instructions about downloading, building and
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booting the OKL4 version of Genode.
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Prerequisites
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#############
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You need Python 2.4 to use the OKL4 build system. On Debian/Ubuntu systems
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simply type:
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! apt-get install python2.4
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Since Ubuntu 10.04, the python2.4 package is no longer part of the official
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repositories. However, you can manually add the repository via:
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! add-apt-repository ppa:python24-team/python24
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! apt-get update
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Moreover, you need to download and install the tool-chain used by Genode. Have
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a look at this page:
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:[http://genode.org/download/tool-chain]:
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Genode tool-chain
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Downloading and building the OKL4 kernel
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########################################
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To download the OKL4 source code, issue
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! make prepare
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from within the 'base-okl4' directory. The Makefile within this directory will
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take care of downloading the kernel's source code and applying the patches
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found at 'base-okl4/patches'.
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For the vesa driver on x86 the x86emu library is required and can be downloaded
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and prepared by invoking the following command from within the 'libports'
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directory:
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! make prepare PKG=x86emu
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To create a build directory for Genode running on OKL4, use the 'create_builddir'
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tool:
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! <genode-dir>/tool/create_builddir okl4_x86 BUILD_DIR=<build-dir>
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Once, you have created the build directory, the OKL4 kernel can be built from
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within '<build-dir>' via
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! make kernel
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Running the Genode demonstration scenario
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#########################################
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For a quick test drive of the OKL4 kernel, issue 'make run/demo' from the build
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directory.
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Manually building a boot image
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##############################
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This section is not needed when using Genode's run-script mechanism. The manual
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steps described below are automatically executed via the OKL4 run environment
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as found at 'base-okl4/run/env'.
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To practically use the OKL4 kernel and applications running on top of it, Open
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Kernel Labs provide a tool called 'elfweaver', that is used to merge different
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application binaries and the kernel itself into one single elf binary that can
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be executed by your bootloader, e.g. Grub.
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To configure 'elfweaver' to merge the appropriated elf binaries you have to
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provide an XML file. A good starting point is the 'weaver_x86.xml' file that
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includes the Genode demo example. Simply copy that file to your Genode build
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directory and adapt the 'file' attribute of the 'kernel' tag to the absolute
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path of the OKL4 kernel we build previously.
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! cp <path_to_genode_src>/base-okl4/tool/weaver_x86.xml weaver.xml
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The corresponding line in your weaver.xml should look like this:
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! <kernel file="<path_to_okl4_src>/build/pistachio/bin/kernel" xip="false" >
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Before creating the image, we need to supply a Genode config file as well.
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For a quick start, you can copy and rename the template provided 'os/config/demo'
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to '<builddir>/bin/config'. Alternatively, you can assign another file to the
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'filename' of the 'memsection' declaration for the config file in 'weaver.xml'.
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Now, we can use 'elfweaver' to create the image. Go to the 'bin' directory in
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the Genode build directory that contains all the binaries and invoke the
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script.
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! cd bin
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! <path_to_okl4_src>/tools/pyelf/elfweaver merge --output=weaver.elf ../weaver.xml
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! strip weaver.elf
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Note: the given paths to the resulting elf file and the input xml file have to
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be relative.
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*Bug alert:* Elfweaver triggers an assertion when too many memsections are
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declared in the 'weaver.xml' file and just outputs the following message
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! An error occurred:
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Apparently, elfweaver has a problem with calculating the size of the boot info
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section. As a quick fix, you can increase the value of 'BOOTINFO_GUESS_OPS' in
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'<okl4-dir>/tools/pyelf/weaver/bootinfo.py'.
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The resulting elf image can be loaded by Grub now.
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Further Information
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###################
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:[http://genode.org/documentation/articles/genode-on-okl4]:
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Article about the porting work of Genode to OKL4, featuring many technical
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insights that are useful to understand the peculiarities of this base platform.
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:okl4_2.1.1-patch.9/README:
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OKL4 building guide
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:[http://wiki.ok-labs.com]:
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OKL4 developer wiki
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:[http://wiki.ok-labs.com/downloads/release-3.0/elfweaver-ref-manual-3.0.pdf]:
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Elfweaver reference manual
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