Kernel Building: Difference between revisions
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#REDIRECT [[Kernel]] |
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;Note: it is recommended that you build an RPM ([[Rebuilding OLPC kernel]]) unless you are already familiar with kernel development! |
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== Building an OLPC kernel == |
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After obtaining the OLPC source (and if desired, making changes), the following steps can be taken to build a kernel on any Fedora Core machine (Fedora 10 tested): |
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Go to the directory where the kernel source is copied (On my machine it is under /home/plug/workspace/olpc/kernel/source) and issue the following commands (issue the command "make help" for details): |
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make $PARAM distclean # Required only when doing a clean build from scratch i.e. all the previous configuration and binary files in this directory will be deleted. |
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make $PARAM olpc_defconfig # The default configuration file for OLPC. Required if building the kernel for the first time. |
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make $PARAM menuconfig # Provides a graphical interface for verifying and/or modifying the default configuration file. |
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make $PARAM # Build the kernel and modules. |
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make $PARAM modules_install # Root access is not required as the $OUTPUTDIR is a user(developer) accessible directory. |
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make $PARAM install # Root access is not required as the $OUTPUTDIR is a user(developer) accessible directory. |
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make $PARAM headers_install # Required only for development platforms. |
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In the above commands replace $PARAM with the following (refer $KERNEL_SRC_DIR/README and $KERNEL_SRC_DIR/Documentation/kbuild/makefiles.txt for details): |
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0=$OUTPUTDIR ARCH=i386 INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=$OUTPUTDIR INSTALL_PATH=$OUTPUTDIR INSTALL_HDR_PATH=$OUTPUTDIR |
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here $OUTPUTDIR is the directory where you want the kernel binary to be copied, e.g. On my build machine it is /home/plug/workspace/olpc/kernel/install. |
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The advantage of having a custom install directory is that you do not require root access and avoid accidentally overwriting the kernel on your build machine. |
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After installing the kernel, go to $OUTPUTDIR and archive the kernel and the modules as follows: |
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tar zcvf kern.tar.gz vmlinuz-$VERS System.map-$VERS /lib/modules/$VERS |
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Replace $VERS above with the proper kernel version that has been built. |
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Assuming everything builds correctly, you will be left with kern.tar.gz. This can be copied over to an XO laptop, and the following steps will install the kernel (again, replacing $VERS with the kernel version). Open the terminal activity on the XO and issue the following commands: |
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su # Change to root. |
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mkdir /tmp/newkern ; cd /tmp/newkernel |
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# Now copy kern.tar.gz to /tmp/newkernel |
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tar zxvf kern.tar.gz |
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cp System.map-$VERS /versions/boot/current/boot/ |
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cp vmlinuz-$VERS /versions/boot/current/boot/ |
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ln -sf /versions/boot/current/boot/vmlinuz-$VERS /versions/boot/current/boot/vmlinuz |
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cp -r lib/modules/$VERS /lib/modules/ |
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If not booting off NAND, you'll probably want to skip the /versions/boot/current/ prefix on the paths above. A limited number of kernel modules are required by the ramdisk during the boot process; if you need to update the ramdisk, these additional steps are also necessary: |
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mkdir /tmp/newrdimg ; cd /tmp/newrdimg |
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zcat /versions/boot/current/boot/olpcrd.img | cpio -i |
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cp -r /lib/modules/$VERS lib/modules/ |
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find . -print | cpio -H newc -o | gzip -9 > /versions/boot/current/boot/olpcrd.img-$VERS |
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ln -sf /versions/boot/current/boot/olpcrd.img-$VERS /versions/boot/current/boot/olpcrd.img |
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Reboot the XO. Open the terminal activity and issue the following command to verify that the XO is running the $VERS kernel: |
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uname -r |
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[[Category:Developers]] |
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[[Category:OS]] |
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[[Category:Software]] |
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[[Category:Build system]] |
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Latest revision as of 14:52, 21 February 2011
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