Outreach Program Projects

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The Xen Project is a Linux Foundation collaborative project that develops the

  • Xen Hypervisor (for x86 and ARM) - the bulk of this page
  • The XAPI toolstack (see #Mirage_OS)
  • Mirage OS (see #XAPI)
  • We also have some infrastructure, tooling and community related projects that run across all the sub-projects. These are slightly different from other projects, in terms of skills: see #Infra_and_Community

The project also has excellent relationships with its upstreams (Linux Kernel, the BSDs, QEMU and other projects) and upstreams such as Linux distributions. This is reflected in the project list, which contains many interesting cross-project development projects for applicants.

Finding a project that fits you

This page lists Xen Project development projects for Outreachy (formerly the Outreach Program for Women) that can be picked up by anyone! If you're interesting in hacking Xen Project code and want to become a part of our friendly developer community this is the place to start! Ready for the challenge?

To work on a project:

  • Find a peer-reviewed project from below that looks interesting. If you do not find an interesting issue, you can also go to Xen UserVoice, pick a few projects from there and ask on xen-devel@ whether the chosen project(s) would be suitable for Outreachy. Note that some of them may be too large or complex for Outreachy.
  • Send an email to the relevant mailing list (see Developer Mailing Lists) and let us know if you are interested in starting to work or applying on a specific project.
  • Post your ideas, questions, RFCs to the relevant mailing list sooner than later so you can get comments and feedback.
  • Easy test projects to fulfil the Make a Small Code Contribution Requirement: An easy way to get started (and show that you can set up the Xen Development Environment, fix an issue, build and test Xen, submit a patch, etc.) is to address a suitable number of Coverity Scan issues. Ask on xen-devel@ for a set of suitable issues and later you may ask for access to coverity scan or for a bug on /bugs.xenproject.org.

You have your own project idea: no problem!

  • If you have your own project idea, outline what you are trying to do on the mailing list. If you know the right list, post your project idea on mailing list. Failing that post on xen-devel and we can redirect you to the right list. Make sure you add OPW 2014 to the subject line.

It is a good idea to ...
The Xen Project has also participated in the Gnome Outreach Program for Women (OPW) and Google Summer of Code (GSoC) in the past. One of the things we learned by participating in these programs is that you will be more successful, happier and get more out of participating in internship programs, if you do a bit of prep-work before writing an application. Here is some stuff you can do:

  • Contact your mentor early and get to know him or her
  • Start hanging out on our IRC channel. You can use the #xen-opw IRC channel on freenode.net for now
  • You may want to ask the mentor for a couple of small bitesize work-items (such as reviewing someones patch, a bitesize bug, ...) and start communicating on the relevant mailing list. That helps you become familiar with our development process, the mentor and other community members and will help you chose the right project and help you decide whether the Xen project is for you.
  • Note that quite a few Xen maintainers used to be GSoC participants once. Feel free to ask community dot manager at xenproject dot org to put you in touch with them if you have questions about their experience.
  • Any work you submit before applying for a project should be based on xen-unstable development tree, if the project is Xen Hypervisor and/or tools related. Linux kernel related patches should be based on upstream kernel.org Linux git tree (latest version). XAPI and Mirage OS patches should be based on the right codeline too. Check out the navigation by audience section on the left to find resources.

More resources

Quick links to changelogs of the various Xen related repositories/trees: Please see XenRepositories wiki page!

Before to submit patches, please look at Submitting Xen Patches wiki page and the relevant Xen Project team page. This will contain more information.

If you have new ideas, suggestions or development plans let us know and we'll update this list!

Aspiring Participants

  • Please contact the mentor and CC the most appropriate mailing list
  • Get a bite-size task from the mentor before the application starts
  • If you feel comfortable with an idea, please put your name to an idea using the following format
|Review=(delete as addressed)
* {{Comment|~~~~:}} I am interested in this idea ... 
                    (note that you may also want to link to the e-mail thread with the mentor)
  • You will need to request write access to the wiki by filling out this form

Outreach Program Project Ideas

List of peer reviewed Projects

Xen Hypervisor Userspace Tools

golang bindings for libxl

Date of insert: 02/11/2016; Verified: 02/11/2016; GSoC: yes
Technical contact: George Dunlap <george.dunlap@citrix.com>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Straightforward
Skills Needed: Familiarity with both C and the Go language
Description: libxl is a robust library designed to be able to drive all necessary interaction with a Xen system; it's the library on which both xl and libvirt-xen are written. The Go programming language (http://ww.golang.org) is a modern language spawned out of Google that aims to be a useful, small, typed language for user-level systems programming. As such, it is an obvious choice to write a control daemon or other system on top of libxl. The goal of this project would be to sketch out an initial implementation of Go language bindings for libxl, along with a test suite to make sure that the interface works and is useable (as well as to serve as a template).
Outcomes: A draft Go interface that appropriately represents the libxl interface (or a useful subset). Code which implements that interface; in particular translating elements from the C interface into Go structures and interacting with the garbage collector. A test / example program to demonstrate the functionality and utility of the interface.

KDD (Windows Debugger Stub) enhancements

Date of insert: 01/30/2014; Verified: 02/11/2016; GSoC: yes
Technical contact: Paul Durrant <paul.durrant@citrix.com>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Medium
Skills Needed: C, Kernel Debuggers, Xen, Windows
Description: kdd is a Windows Debugger Stub for Xen hypervisor. It is OSS found under http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=tools/debugger/kdd;h=fd82789a678fb8060cc74ebbe0a04dc58309d6d7;hb=refs/heads/master

kdd allows you to debug a running Windows virtual machine on Xen using standard Windows kernel debugging tools like WinDbg. kdd is an external debugger stub for the windows kernel. Windows can be debugged without enabling the debugger stub inside windows kernel by using kdd. This is important for debugging hard to reproduce problems on Windows virtual machines that may not have debugging enabled.

Expected Results:

  1. Add support for Windows 8.1 and 10 (x86, x64) to kdd
  2. Add support for Windows Server 2012 to kdd
  3. Enhance kdd to allow WinDbg to write out usable Windows memory dumps (via .dump debugger extension) for all supported versions
  4. Produce a user guide for kdd on Xen wiki page
Nice to have: Allow kdd to operate on a Windows domain checkpoint file (output of xl save for e.g.)
Outcomes: Code is submitted to xen-devel@xen.org for inclusion in the xen-unstable project.

Add PVH mode support to OVMF (UEFI)

Date of insert: 18/02/2016; Verified: 18/02/2016; GSoC: Yes
Technical contact: Roger Pau Monné <roger.pau@citrix.com>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Medium
Skills Needed: Strong C skills, x86 architecture knowledge.
Description: OVFM already has quite a lot of Xen support, including a xenstore, grant-table, xenbus and blkfront implementations. The applicant should be able to leverage all this features in order to create a OVMF binary that’s capable of running as a PVH guest. The student is expected to complete the following tasks:
  • Add support for the PVH entry point to OVMF.
  • Detect which devices OVMF makes use of (local APIC, uart, i8259…).
  • Replace the usage of the emulated devices that are not available with their para-virtualized counterparts.
In order to complete this tasks the student will need to read and understand the PVH interface draft . It’s also important to notice that FreeBSD contains the implementation of all the needed para-virtualized devices under a BSD license, which is compatible with the license used by OVMF.
Outcomes: By the end of the project OVMF should work as a PVH kernel, and should be capable of loading other PVH capable guests/firmwares.

Xen Toolstack

QEMU xen-blkback performance analysis and improvements

Date of insert: 15/02/2016; Verified: 15/02/2016; GSoC: Yes
Technical contact: Roger Pau Monné <roger.pau@citrix.com>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Medium
Skills Needed: Strong C skills, ability to read and understand a protocol
Description: The current xen-blkback implementation inside of QEMU is lacking several features found in the in-kernel Linux xen-blkback implementation. The student should analyze the bottlenecks currently found in QEMU, and provide solutions in order to reduce them. Some of them might involve:
  • Use grant-copy instead of grant-map.
  • Implement support for indirect descriptors.
  • Implement multi-queue support.
There's a reference implementation of the last two items in the xen-blkback code in Linux, and a technical document that describes the protocol extensions in the Xen public headers.
Outcomes: By the end of the project, the student should provide a detailed performance analysis of the block backend inside of QEMU, and implemented at least one performance improvement of a sizeable magnitude or several smaller ones.

Consolidating adhoc parsers in xl

Date of insert: 16/02/2016; Verified: 16/02/2016; GSoC: Yes
Technical contact: Wei Liu <wei.liu2@citrix.com>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Easy to Medium
Skills Needed: Strong C skill, knowledge of GNU make and autotools, bonus point: knowledge of flex / bison and / or Haskell / OCaml parsec library
Description: Xl has accumulated a lot of adhoc parsers over time. They also tend to be easily broken by followup changes. This project aims to consolidate all adhoc parsers into either a set of functions or into libxlutils (which is a library for parsing user input) and provide a test suite for it.

You can write everything in C. Better yet it should be made easily extensible with flex / bison or Haskell / Ocaml parsec library. The test suite should be integrated into Xen's build system.

The description is quite vague because there are more than one way of doing it. Feel free to send me your idea or ask for more information by email.
Outcomes: A set of APIs for parsing configurations. A test suite for testing those APIs.

Xen Hypervisor

Icon todo.png To Do:

Have a shortlist of new projects that will be added shortly

Rump Kernel

Icon todo.png To Do:

Have a shortlist of new projects that will be added shortly

Mirage OS

Several different projects (follow link)

For Mirage OS, please check out the Mirage OS Pioneer-Projects page. If you are interested in one of these projects, please e-mail mirageos-devel@lists.xenproject.org and CC the mentor from the page (the project will contain a link to the mentor's GitHub account, which normally contains an email address and IRC information). You can also ask questions on the #mirage IRC channel and usually find mentors on there.


No projects at this stage.

Infra and Community

We also have some infrastructure, tooling and community related projects that run across all the sub-projects. These are slightly different from other projects, in terms of skills and working with the community. Please check extra information below the project.

Xen Code Review Dashboard

Date of insert: 16/02/2016; Verified: 16/02/2016; GSoC: Yes
Technical contact: Jesus M. Gonzalez-Barahona <jgb@bitergia.com>, Lars Kurth <lars.kurth@xenproject.org>
Mailing list/forum for project: xen-devel@
IRC channel for project: #xen-devel
Difficulty: Medium
Skills Needed: SQL, Java/Javascript, HTML5/XML skills, basic software design knowledge (working with the mentors)
Description: The code review process in Xen is being analysed using MetricsGrimoire tools (correlating email based reviews with git commits in Xen Project trees to cover the entire workflow). The data is then stored in an SQL database and visualised using a Kibana based dashboard and some custom reports (e.g. [1]). The main objectives of this project is to extend the existing tools, to
  1. To produce a Perceval-based script to analyse the code review messages in Xen (instead of the original MLStats/CVSAnalY-based scripts). This would include taking the output of our current prototype scripts, and converting them into a more mature script, using information produced by Perceval.
  2. To enrich that information as is needed, based on existing custom reports, to produce the ElasticSearch indexes that we use for the dashboards.
  3. If time, to work with the Xen Project developer community on extending the dashboards themselves (note that this part may not be needed and depends on engagement with the developer communities' needs).
  4. If time, we could consider testing/extending the heuristics developed for Xen Project to work with other Linux-related projects, and maybe Linux itself.

All scripts, widgets and code developed as part of this project will be made available under open source licenses to either GitHub or a code repository hosted on xenbits.xen.org/gitweb.

Related open source technologies and repositories:

  • TODO: Add links to the github location of the dashboard and other scripts, if needed

Further Information:

  • Small code contribution requirement: Ask the mentors for a small task, based on an initial discussion.
  • IRC: #metrics-grimoire at freenet (mentors are jgbarah and lars_kurth)
  • Mailing List: : metrics-grimoire@lists.libresoft.es and CC xen-devel@lists.xenproject.org
  • Final Code Location: Decide final code location of output
Outcomes: The final result is to enable the code review dashboard to add additional views, possibly augment the database and improve the heuristics of the existing prototype tools.

New Project Ideas

Please add new project ideas here, following

Conventions for Projects and Project Mentors

Rules and Advice for Adding Ideas

  • Be creative
  • Add projects into New Project Ideas or improve projects in Project Ideas that Need Review or more work through review comments.
  • Use the {{GSoC Project}} template to encode ideas on this page. Please read the Template Documentation before you do so.
  • Be specific: what do you want to be implemented; if at all possible provide an indication of size and complexity as described above to make it easier for an applicant to choose ideas
  • If you are willing to mentors those ideas, add your name and email to the idea.
  • Aspiring mentors should introduce themselves on the most appropriate Xen Project mailing list

Peer Review Goals

We strongly recommend and invite project proposers and project mentors to review each others proposals. When you review, please look out for

  • Can an intern get going and started with the information in the project description
  • Are any unstated assumptions in the proposal, is there undefined terminology, etc. in the proposal
  • Can the project completed in 3 months (assume that one month is needed for preparation)
  • Does the project meet Google Summer of Code goals, which are
    • Create and release open source code for the benefit of all
    • Inspire young developers to begin participating in open source development
    • Help open source projects identify and bring in new developers and committers
    • Provide interns the opportunity to do work related to their academic pursuits (think "flip bits, not burgers")
    • Give interns more exposure to real-world software development scenarios (e.g., distributed development, software licensing questions, mailing-list etiquette)

Peer Review Conventions

The {{GSoC Project}} template used to encode project listings, contains some review functionality. Please read the Template Documentation before you add a template, also please use the conventions below to make comments.

|Review=(delete as addressed)
* {{Comment|~~~~:}} Comment 1
* {{Comment|~~~~:}} Comment 2

Choosing Projects

We have a bi-weekly mentor meeting overlooked by our program management team, which are a core team of 2-3 mentors and a program administrator. This group will work with mentors to ensure that project proposals are of good quality and whether mentors are engaging with the program management team and particpants in the weeks before the application period ends.