10Jan2019 WIP
This repository contains materials such as notes, patches, build logs scriptlets and similar items that may be useful in building Linux From Scratch (LFS) and Beyond LFS (BLFS) on CPU architectures other than x86 and x86_64 (aka IA).
Information in this repository has originated from various sources. Any derivative material in this repository retains the original authors Copyright and is used in this repository under the license terms associated with the original work. All original information in this repository is Copyrighted by the author Tom Armistead and is provided in this repository under the terms of the Creative Commons license.
The contents of this repository is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability.
THERE IS NO WARRANTY FOR THESE MATERIALS, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM AS IS WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
The LFS book specifically targets building an LFS system only for x86/x86_64 based machines. Although many of the instructions in the LFS also work in building LFS on a non x86/64 machine, there are a number of changes in the book instructions that are needed to accomplish an LFS build on other CPU architectures. The purpose of this respository is to document those changes in the hope that it may be useful to developers who wish to build LFS/BLFS on non x86/64 architectures.
Materials in this repository are most often tested with the sysvinit version of the LFS book. Periodically they have been tried with the systemd version of the book and also seem to work for systemd builds but if you want to stay on the road most traveled the sysvinit version is it.
Materials in this repository won't work with the multi-lib variant of the LFS. Only supports pure 64 or pure 32 bit builds.
If you are using this repository to build LFS and run into difficulties building LFS on non x86/64 machines, please DO NOT ask questions on the LFS website. By intention, the LFS book specifically targets only x86/64 so any questions or problems building on other architectures are not appropriate for the main LFS site. If you run into problems, file an issue in this repository or work through the issue yourself.
If you are specifically interested in LFS for RaspberryPI, you may find pilfs (http://intestinate.com/pilfs/ ) to be useful. Pilfs provides tarballs, scripts and such that make it very easy to run LFS on your Pi board. This repository provides information that is more general in nature regarding building LFS on nonIA boards and doesn't provide tarballs or turnkey solutions like those which can be found in pilfs.
This repository consists of a main level which contains this README and other information which may be of general use in building LFS and subdirectories which coorespond to a specific LFS releases and contain information specific to that particular release.
Currently there are six subdirectories: lfs90, lfs84 to lfs81 and lfs79, cooresponding to LFS releases 9.0 to 7.9. All materials herein should be considered as WIP but have been used to build an LFS system for some of ppc64, ppc32, ARM32 and ARM64 (aarch64).
Due to lack of machines to test on, building LFS on MIPs and other
architectures beside ppc and arm is not part of this repository.
Building on some ppc variants such as E500 machines is also an unknown.
The contents of each lfs subdirectory varies a bit but will contain at least a LFS book patch (lfs-book.patch) in the 'patches' subdirectory. The LFS book patch is the main thing. It modifies the LFS book such that the instructions in it will work for additional architectures besides Intel. Each directory also may contain notes, jhalfs patches, source code bits and pieces, build logs, kernel config files and other information specific to building that release on various architectures.
This repository contents would typically be used (with jhalfs for the build tool) as follows:
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Obtain a local copy of the LFS book (in XML format) using subversion or otherwise.
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Find the LFS book patch in the patches subdirectory and apply it to the local copy of the LFS book. 2a) If doing a "cut and paste" build, render the patched book into human easily readable form (skip the jhalfs stuff) and build from it.
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Obtain a copy of jhalfs using subversion and make any changes needed. The patches subdirectory may contain jhalfs patch(s) that will help with this step. 3a) Arch specific custom configs can be added to the jhalfs build if desired.
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Initiate the build of LFS using jhalfs pointed at the local (working) copy of the patched LFS book.
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Copy any extra LFS package patches from the patches directory to the sources directory of the LFS build area.
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Once the jhalfs build of LFS is complete, chroot into the LFS build and build any extra tools needed for the architecture. Build the kernel and bootloader as needed for the architecture.
Note that the book patch concentrates on changes to the build instructions and not so much on the descriptive text. If you are cut and pasting from the rendered book, be aware that the descriptive text may sometimes not exactly match the modified build instructions
This section provides general information regarding building LFS on non-IA CPUs. Additional detailed information regarding building LFS for specific architectures and for specific LFS versions can be be found in other READMEs or documents.
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LFS_TGT will likely need to be modified.
The default LFT_TGT target variable value may not work properly for nonIA architectures. (Although the default LFS_TGT works ok for PowerMac builds). It may need to be modified to a value that works for the architecture that you are building on.
A mistake in the LFS_TGT setting will likely not be discovered until some hours of time have been spent building packages. So, it is worth spending some time on getting this set properly before starting the build.
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Jhalfs may need to be modified.
Note also that if building LFS with jhalfs, a modification may be needed to the jhalfs code itself to set the LFS_TGT properly. jhalfs does not read and use the value of LFS_TGT from the book source but instead sets the LFS_TGT value in one of it's scripts. So, if you have to modify LFS_TGT for your target, you will also have to make an adjustment to jhalfs.
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SWAP space will likely be needed.
Enabling SWAP space is crucial. Many nonIA boards have limited amounts of RAM and the LFS build will not complete without access to a SWAP partition. Even with SWAP space, attempting to build LFS on a board with less than 256Meg of DRAM will not likely succeed.
Some boards primarly use SD cards or USB flash drives for storage. If possible, use regular hard disk (or ssd) drives for the swap area and also for the LFS build area. This will speed up the build up a bit vs using usb flash drives or sd cards.
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Be prepared for long build times.
Patience is crucial. The lower CPU speeds,small caches, and limited RAM of nonIA boards means that an LFS build will likely take some days. (e.g. a build of LFS 8.1 with all final test suites enabled on a 700Mhz ppc G3 required nearly 120 hours of compile time.)
Using fast media (like an actual hard disk) for the LFS and swap areas may help speed up the build on SD/flash based machines.
It's best to patch (if needed) jhalfs to build for your machine and let it take care of doing the long build.
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The bulk of the needed changes will be in LFS Chapter 05.
Typically, most of the changes needed to build LFS on nonIA board are in the building of the tool chain packages. In particular, the build of GCC pass1 and pass2 in Chapter 5 will almost certainly require changes to work with non-IA CPUs. But there will likely be other changes needed besides the tool chain.
Note: The LFS patches sometimes don't work for non-IA boards. e.g. In the LFS8.3 the chap6 coreutils patch causes problems for PPC32 builds.
Most BLFS packages seem to build ok as is on non-IA machines. But then again, only a small set of them have been built by this author.
The blfs tool itself seems to function properly on PPC and ARM systems without any changes needed.
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Skip building Grub on non-IA boards.
grub is specific to the IA boards and is not needed on nonIA boards. It does not likely need to be built for a non IA board.
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Serial console may need to be enabled.
Many nonIA boards have no graphics display and are accessed through serial console. A change to /etc/inittab is required to enable login via serial console.
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Non standard kernel and bootloader code may be needed.
Appropriate kernels and bootloaders for the LFS build will have to be tracked down. The kernel version listed in the LFS book may not work for the board of interest. The kernel code may need to be obtained from a non standard repository and/or may need to be patched. Additional tools may need to be built in order to even build the kernel. The same is true for whatever bootloader is needed.
Finding working kernel source is often a challenge. Googling may find many possible sources of a kernel for a particular board and it's not clear which one(s) will work well.
The kernel referenced in the LFS book can be used to build the kernel headers even if the kernel itself is built from another source base. (as long as it is a reasonably recent kernel version).
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Make sure the clock is set accurately
If the system clock is not set to a reasonably accurate value, some packages will not build properly. Clock setting is not typically a concern on most IA computers but many hobbyist type of boards do not have a built in clock and expect the time to be set manually or via network. An incorrect clock value can cause build problems.
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Next
Materials that may be helpful for building specific LFS releases may be found in the release subdirectories within this repository.