Outreach Program Projects

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

• Xen Hypervisor (for x86 and ARM) - the bulk of this page. IRC channel #xendevel
• Unikraft (see #Unikraft). IRC channel #unikraft
• Mirage OS (see #Mirage_OS). IRC channel #mirage
• 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 Google Summer of Code and Outreachy (formerly the Outreach Program for Women). But projects 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:

• 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.
• 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.
• Small Contribution Requirement: Outreachy requires that youfulfil the Make a Small Code Contribution Requirement. This is not strictly necessary for GSoC, but a small contribution to the project during the application period gives you an advantage

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 Outreachy <round> or GSoC <year> to the subject line.

It is a good idea to ...
The Xen Project has participated in Outreachy 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 channels (#xendevel, #unikraft, #mirage)
• 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). 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

{{project
...
|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

List of peer reviewed Projects

Xen Hypervisor Userspace Tools

golang consumer for the `xenlight` golang package Date of insert: 28/01/2020; Verified: 28/01/2020; GSoC: yes Technical contact: George Dunlap <george.dunlap@citrix.com>, IRC nick: gwd Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate# IRC channel for project: #xendevel Difficulty: Straightforward Skills Needed: Familiarity with the Go language Description: The `xenlight` golang package consists of golang bindings for libxl, 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 golang bindings are nearing completion, and so this project would be to create an in-tree consumer of those bindings; partly as an example, partly to be useful. Ideas include: A simple `host status` daemon which would present information about the host: memory available, domains running, and so on A 'system stress tester', which would perform random operations (create / destroy / migrate / suspend VMs, create / destroy / migrate cpupools, &c) in quick succession to test the robustness of the system A re-implementation of the 'xl' command in Golang, suitable to be used as a drop-in replacement in our test system A 'wrapper' library to make creation of guests simple and straightforward, with a minimum of boilerplate Applicants are encouraged to come up with their own ideas as well. Outcomes: A useful project or library which exercises and demonstrates how to use the `xenlight` golang package.

Xen Hypervisor

Xen on ARM: Trap & sanitize ID registers (ID_PFR0, ID_DFR0, etc) Date of insert: 01/02/2019; Verified: 01/28/2020; GSoC: Yes Technical contact: Stefano Stabellini <sstabellini@kernel.org>, IRC nick: sstabellini; Julien Grall <julien@xen.org>, IRC nick: julieng Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel Difficulty: Medium Skills Needed: Good C and kernel programming skills Description: Booting Xen on new big.LITTLE hardware might crash Xen because we expose the registers to guests without sanitizing them first. They don't reflect the virtual platform exposed to guests. We need to trap these registers, sanitize them, them return the sanitized value to the guest. The challenge is to identify all the registers of the ID_ family that we need to trap and figure out what is the right sanitization required for each of them to reflect the virtual platform exposed to the guest. Outcomes: ID_ register accesses are trapped into Xen and sanitized by the hypervisor

Xen on ARM, dom0less: configurable memory layout for guests Date of insert: 01/02/2019; Verified: 01/28/2020; GSoC: Yes Technical contact: Stefano Stabellini <sstabellini@kernel.org>, IRC nick: sstabellini; Julien Grall <julien@xen.org>, IRC nick: julieng Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel[Outreachy] as appropriate Difficulty: Medium Skills Needed: Good C and kernel programming skills Description: Dom0less guests are guests loaded into memory by the uboot bootloader and started directly by Xen at boot time in parallel with dom0. They are configured via device tree, see docs/features/dom0less.markdown and docs/misc/arm/device-tree/booting.txt. This project is about adding more device tree bindings so that dom0less guests can have a completely configurable memory layout, where the normal memory start address and the address of the other virtual MMIO regions can be specified by the user. As an extra, it would be nice to allow two or more dom0less guests to share a page in memory among them. Outcomes: Dom0less guests have a configurable memory layout

ARMv8.1 atomics Date of insert: 01/02/2019; Verified: 01/28/2020; GSoC: Yes Technical contact: Stefano Stabellini <sstabellini@kernel.org>, IRC nick: sstabellini; Julien Grall <julien@xen.org>, IRC nick: julieng Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel Difficulty: Medium/Hard Skills Needed: Good C, assembly, and kernel programming skills Description: Introduce the usage of the new ARMv8.1 LSE atomic instructions in Xen. The new instructions can be used to implement basic bit manipulation functions and other important atomic operations, such as xchg, cmpxchg, etc. See the current atomics implementation under xen/arch/arm/arm64/lib. Outcomes: The new ARMv8.1 LSE instructions are used to implement atomic functions in Xen

Xen on ARM: dynamic virtual memory layout Date of insert: 01/02/2019; Verified: 01/28/2020; GSoC: Yes Technical contact: Stefano Stabellini <sstabellini@kernel.org>, IRC nick: sstabellini; Julien Grall <julien@xen.org>, IRC nick: julieng Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel Difficulty: Hard Skills Needed: Good C and kernel programming skills Description: Today Xen is limited in the virtual address ranges it can use to map physical pages. This project is about introducing more flexibility in the Xen pagetable handling code to be able to map pages at any virtual addresses. Outcomes: Xen can map physical pages at any virtual address.

Xen on ARM: Performance Counters Virtualization Date of insert: 01/02/2019; Verified: 01/28/2020; GSoC: Yes Technical contact: Stefano Stabellini <sstabellini@kernel.org>, IRC nick: sstabellini; Julien Grall <julien@xen.org>, IRC nick: julieng Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel Difficulty: Hard Skills Needed: Good C, assembly, and kernel programming skills Description: Performance counters are a family of ARM registers used to measure performance. Today they are not virtualized by Xen, they are just trapped and implemented as read-as-zero/write-ignore, see xen/arch/arm/arm64/vsysreg.c and xen/arch/arm/arm64/vsysreg.c. This project is about properly virtualizing these registers, so that guests can use them to measure their own performance. It involves saving and restoring the performance counters registers in Xen during VM context switch. Outcomes: Xen guests can use performance counters.

Unikraft

Unikraft is a unikernel build system that enables developers to build light-weight services starting from a highly customizable library base. This library base includes core libraries which provide decomposed OS functionality (e.g., schedulers, memory allocators, etc.) and enhanced libraries that provide functionality to unikernels that is often required by applications (e.g., libC, network stacks). For instance, on x86_64 Unikraft is able to automatically generate a (Micro)-python unikernel weighing in at only ~700KBs.

For more information please checkout: [1]

Unikernel QEMU/Stub Domains Date of insert: 09/01/2020; Verified: 09/01/2020; GSoC: Yes Technical contact: Simon Kuenzer <simon.kuenzer@neclab.eu>, IRC nick: skuenzer; Felipe Huici <felipe.huici@neclab.eu> Mailing list/forum for project: Make sure you CC minios-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #unikraft Difficulty: Medium Skills Needed: Good C skills, good kernel programming skills, familiarity with Xen, good understanding of operating system concepts. Description: The Xen architecture has the concept of "stub domains", where, in principle, dom0 functionality can be dissagregated onto multiple, separate VMs that together mimic the overall functionality of dom0. This improves reliability, performance/scalability and flexibility. This project consists of generating different stub domains based on Unikraft by porting the XenStore and QEMU to Unikraft. Outcomes: Considerably increasing Xen's flexibility, scalability and reliability through unikernel-based stub domains.

Mirage OS

Several different projects (follow link)

For Mirage OS, please check out the list of Mirage OS projects where help is needed. 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.

XAPI

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.

Add Centos Virt SIG Xen packages test to the CentOS CI loop Date of insert: 18/02/2016; Verified: 16/01/2019; GSoC: Yes Technical contact: George Dunlap <george.dunlap@citrix.com>, IRC nick: gwd Mailing list/forum for project: Make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate IRC channel for project: #xendevel Difficulty: Easy Skills Needed: Basic shell scripting Description: The CentOS project has a continuous integration (CI) system running Jenkins, which can automatically run a set of tests when specific conditions are met, such as new versions of packages being available on the CentOS community build system (CBS). The CentOS Virtualization SIG ('Special Interest Group') produces Xen packages for CentOS 6 and 7, along with other related packages (such as libvirt). The goal of this project would be to add tests to this system to test the basic functionality of the Xen packages produced by the CentOS Virt SIG, helping to avoid regressions in released software. Outcomes: An appropriate array of tests for xen (and ideally libvirt) packages running in the CentOS CI loop.

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.

Projects completed in 2017

Fuzzing Xen hypercall interface This project was completed by Felix Schmoll For more information see My GSoC experience: Fuzzing the hypervisor Technical Summary of project GSoC 2017 Date of insert: 8/02/2017; Verified: 8/2/2017; GSoC: Yes (accepted in 2017 - see https://summerofcode.withgoogle.com/dashboard/project/5585891117498368/overview/) Technical contact: Wei Liu <wei.liu2@citrix.com>; make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate Difficulty: Very high Skills Needed: Strong C and ASM skills, good knowledge of GCC toolchain, good knowledge of GNU Make, good knowledge of fuzzing in general, good kernel programming and user space programming skills Description: The Xen Project has been using American Fuzzy Lop (AFL) for fuzzing and achieve useful results. Up until now we've only been able to adapt some Xen components to be fuzzed in a userspace program. There is untapped potential in using AFL (or other fuzzers) to fuzz hypercall interface. AFL (and other coverage guided fuzzers) requires feedback from the fuzzing target to mutate test cases. Xen does not yet have the ability to return precise execution path. Create a small domain or program to accept command from fuzzer, execute test case etc. Use GCC coverage support to give back precise execution path. Massage and feed the input back to fuzzer. Related open source technologies and repositories: AFL home page (and README) Shows how conceptually similar problems have been solved elsewhere Outcomes: A system for fuzzing Xen hypercall interface.

Share a page in memory from the VM config file This project was completed by Zhongze Liu For more information see My GSoC Experience: Allow Setting up Shared Memory Regions between VMs from xl Config File GSoC 2017 Date of insert: 28/02/2017; Verified: 28/2/2017; GSoC: Yes (2017) Technical contact: Stefano Stabellini <sstabellini@kernel.org>; Julien Grall <julien.grall@arm.com>; make sure you CC xen-devel@lists.xenproject.org on all communications; tag mails with [GSoC] or [Outreachy] as appropriate Difficulty: Average Skills Needed: Good C and kernel programming skills Description: Virtual machines use grant table hypercalls to setup a share page for inter-VMs communications. These hypercalls are used by all PV protocols today. However, very simple guests, such as baremetal applications, might not have the infrastructure to handle the grant table. This project is about setting up a shared page for inter-VMs communications directly from the VM config file. So that the guest kernel doesn't have to have grant table support to be able to communicate with other guests. introduce a new VM config option in xl allocate a page in memory and add it to the VM stage2 pagetable at a given address the page should be shareable with other virtual machines Outcomes: A new VM config file option is introduced to share a page in memory across multiple guests