This is a slight modification to crosstool-ng which allows building a bare metal GCC toolchain with OpenMP enabled. Normally OpenMP is only enabled for operating systems such as Linux which have threading and an implementation of libgomp. This variant produces toolchains which compile OpenMP code for bare metal (ARM EABI) systems for which threading and libgomp do not already exist.

The modifications have been developed and tested on a Windows 10/Cygwin system. It is possible to produce a toolchain using Cygwin which can be ported to and used on a non-Cygwin Windows PC.

This is all very experimental. At this point I have been able to demonstrate OpenMP code on a single-core Cortex-M7 (STM32H743) with four software threads. Running OpenMP on a single-core platform is sort of pointless, but the board and development support are cheap and easy to use. Once I develop the infrastructure it will be easy to port to a multi-core platform later. Raspberry Pi is a cheap multi-core platform, but it is not supported by Segger J-link and there is no inexpensive trace suport. Perhaps i.MX6 or i.MX8 (Google Coral) may work out.

The remainder of this README is the same as the original.

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Crosstool-NG aims at building toolchains. Toolchains are an essential component in a software development project. It will compile, assemble and link the code that is being developed. Some pieces of the toolchain will eventually end up in the resulting binaries: static libraries are but an example.

Before reporting a bug, please read bug reporting guidelines. Bugs that do not provide the required information will be closed without explanation.

Refer to documentation at crosstool-NG website for more information on how to configure, install and use crosstool-NG.

Note 1: If you elect to build a uClibc-based toolchain, you will have to prepare a config file for uClibc with <= crosstool-NG-1.21.0. In >= crosstool-NG-1.22.0 you only need to prepare a config file for uClibc(or uClibc-ng) if you really need a custom config for uClibc.

Note 2: If you call ct-ng --help you will get help for make(2). This is because ct-ng is in fact a make(2) script. There is no clean workaround for this.

To clone the crosstool-NG repository:

git clone https://github.com/crosstool-ng/crosstool-ng

These are the old Mercurial repositories. They are now read-only: http://crosstool-ng.org/hg/

You can find open Pull Requests on GitHub here and you can find open issues here.

To contribute to crosstool-NG it is helpful to provide as much information as you can about your change, including any updates to documentation (if appropriate), and test... test... test.

• Fork crosstool-ng on github
• Clone the fork you made to your computer

git clone https://github.com/crosstool-ng/crosstool-ng

• Create a topic branch for your work

git checkout -b fix_comment_typo

• Make changes
• hack
• test
• hack
• etc...
• Add your changes

git add [file(s) that changed, add -p if you want to be more specific]

• Verify you are happy with your changes to be commited

git diff --cached

• Commit changes

git commit -s

The -s automatically adds your Signed-off-by: [name] <email> to your commit message. Your commit will be rejected without this.

Also, please explain what your change does. "Fix stuff" will be rejected. For examples of good commit messages, read the changelog.

• Push your topic branch with your changes to your fork

git push origin fix_comment_typo

• Go to the crosstool-ng project and click the Compare & pull request button for the branch you want to open a pull request with.
• Review the pull request changes, and verify that you are opening a pull request for the appropriate branch. The title and message should reflect the nature/theme of the changes in the PR, say the title is Fix comment typos and the message details any specifics you can provide.
• You might change the crosstool-ng branch, if you are opening a pull request that is intended for a different branch. For example, when you created your topic branch you could have done:

git checkout -b fix_out_of_date_patch origin/1.22

Then when you get to this pull request screen change the base branch from master to 1.22

• By creating a pull request, the PR is entered into the backlog. A travis-ci job will run to test your changes against a select set of samples. As they start to get worked, they should be placed in the Ready state. PRs that are being worked are In Progress. If a questions come up about the commit that might involve changes to the commit then the PR is placed in Waiting For Response, you have two options:

1. Fix the issue with the commit by adding a new commit in the topic branch that fixes the code review. Then push your changes to your branch. This option keeps the comments in the PR, and allows for further code review. I personally dislike this, because people are lazy and fix reviews with fix more review issues. Please make good commit messages! All rules about commits from above apply! THIS IS PREFERED

Add your changes

git add [file(s) that changed, add -p if you want to be more specific]

Verify you are happy with your changes to be commited

git diff --cached

Commit changes

git commit -s

• Push your topic branch with your changes to your fork

git push origin fix_comment_typo

At this point the PR will be updated to have the latest commit to that branch, and can be subsequently reviewed.

2. Interactively rebase the offending commit(s) to fix the code review. This option is slightly annoying on Github, as the comments are stored with the commits, and are hidden when new commits replace the old commits. They used to disappear completely; now Github shows a grey 'View outdated' link next to the old commits.

This recipe also comes handy with other issues, like your topic branch not being up-to-date with master:

git fetch --all
git rebase --ignore-whitespace origin master
git rebase -i <offending-commit-id>^

NOTE: The --ignore-whitespace stops git apply (which is called by rebase) from changing any whitespace when it runs.

Replace pick with edit or remove the line to delete a commit. Fix the issue in the code review.

git add [file(s)]
git rebase --continue
<update commit comment if needed>
git push --force origin fix_comment_typo

We previously used patchwork for development, but it is no longer used. I'd like to see patches that are still applicable turned into Pull Requests on GitHub.

You can find the list of pending patches available on patchwork.

You can find all of this and more at crosstool-ng.org

Report issues at the project site on GitHub.

We have a mailing list. Archive and subscription info can be found here: https://sourceware.org/ml/crossgcc/

Aloha! :-)