Contribution Guidelines

We want to see people contributing to the Xen Project effort, and there are many ways to do so.

As with any open source project, providing concrete contributions will demonstrate to the project leaders that you are serious about being involved, which helps us separate the people who talk about contributing from the people who actually contribute to the project in a meaningful way. This builds trust in your work, and the people who consistently contribute good work will be given more and more responsibility.

Our goal is to maintain an environment of professionalism, respect, and innovation within Xen Project development.  Please adhere to the following guidelines as you participate in the Xen Project community:

  • Be professional in all communications. Please avoid flaming, profanity, vulgarity, SHOUTING IN ALL CAPS. Keep personal discussion for the IRC channel. There is never any reason to publicly discuss gender, ethnicity, orientation, lifestyle, or religion in our project.
  • Stay on topic. If you have a comment that is not relevant to the current discussion, please start a new thread.
  • Keep it legal. Please use project resources for their intended purpose.
  • Don't feed trolls. Every open project attracts unwelcome commentary from individuals trying to get a rise out of someone. When this happens, just ignore them.

Contributing Code

Because every open source project has slightly different policies for accepting code contributions, here are some specific guidelines for contributing to The Xen Project codebase.

Contributions to the Xen Project codebase follow the conventions as they are known in the Linux Kernel community. In summary, contributions are made through patches that are reviewed by the community.  The project does not require community members to sign contribution or committer agreements. We do require contributors to sign contributions using the sign-off feature of the code repository, following the same approach as the Linux Kernel does (see Developer Certificate Of Origin).

In addition, each Xen Project subroject (also called team) may have its own mailing list, submission guidelines, IRC channel, and culture. Please check the team portal to learn more.

The majority of our projects have some shared conventions:

You can also ask questions on the mailing list or any of the subproject lists and irc channels.

Submitting Patches to the Xen Project Codebase

Please first check the submission process for the Xen Sub-Project, and send an email to the proper mailing list with [PATCH] as the first word in the subject line.   Each patch should perform a single function.  Patches sent to the mailing lists should be broken up into several email messages of less than 100KB each, with only one patch per email.

Please include a description of why you want the change made (not just the "what") and why it is important for the team to make this change. Your patch will need to include a signed-off-by tag, author's name, and other information.

For details about what to include in your patch, you should start with the patch submission documentation.


In a project of this size, patches sometimes slip through the cracks. If you submitted a patch to the xen-devel mailing list or bugzilla and did not receive a response within 5 business days, please send an email to xen-devel and in the first line of that email, include this phrase "Patch escalation: no response for x days".

This is one case where you should "top post" to make sure that the escalation text is read.

Code Security Scanning

The Xen Project is registered with the "Coverity Scan" service which applies Coverity's static analyser to the Open Source projects. The tool can and does find flaws in the source code which can include security issues. Currently only the Xen Project Hypervisor (i.e. xen.git) is covered by these scans.

Triaging and proposing solutions for the flaws found by Coverity is a useful way in which Community members can contribute to the Xen Project. However because the service may discover security issues and the Xen Project practices responsible disclosure as described in "Xen Security Problem Response Process" the full database of issues cannot simply be made public.

Members of the community may request access to the Coverity database under the condition that for any security issues discovered, they:

  • agree to follow the security response process.
  • undertake to report security issues discovered to the security team ( within 3 days of discovery.
  • agree to disclose the issue only to the security team and not to any other third party.
  • waive their right to select the disclosure time line. Discoveries will follow the default time lines given in the policy.

Requests should be made to the public mailing list. The request must:

  • use a subject line prefixed "[COVERITY ACCESS] ".
  • signal acceptance of the above conditions.
  • include a short bio of the requester, covering who they are, what, if any, their previous involvement with Xen has been (with references to patches etc), their security background and if they have not been previously involved with Xen why they are interested specifically in the Xen project.
  • be signed by a PGP key which is part of the strong set of the PGP web of trust [1].

These last two items serve to help validate the identity and trustworthiness of the person since they will be given access to potentially sensitive information.

Seven days will be given for responses. Following the "Consensus Decision Making" process described in the project governance document. The request must be publicly seconded ('+1') by at least one maintainer. Objections ('-1') may be raised but must contain a rationale.

[1] PGP Web of Trust:

In practice this will be taken to mean that there is a path from a member of the security team's key to the key. Several members of the security team have keys in the strong set.