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== Project idea template ==
== Project idea template ==

Revision as of 15:03, 6 February 2017

Introduction

QEMU is applying for Google Summer of Code 2017. This page contains our ideas list and information for students and mentors. Google Summer of Code is a program that pays students for 12-week full-time remote work on open source projects from May to August!

Students: Google has not published the list of accepted organizations yet. You are welcome to contribute to QEMU and contact mentors for project ideas you are interested in. Please keep in mind that QEMU may not be accepted into GSoC to avoid disappointment.

Application Process

After contacting the mentor to discuss the project idea you should fill out the application form at [1]. The form asks for a problem description and outline of how you intend to implement a solution. You will need to do some background research (looking at source code, browsing relevant specifications, etc) in order to form an idea of how to tackle the project. The form asks for an initial 12-week project schedule which you should create by breaking down the project into tasks and estimating how long they will take. The schedule can be adjusted during the summer so don't worry about getting everything right ahead of time.

Candidates may be invited to an IRC interview with the mentor. The interview consists of a 30 minute C coding exercise, followed by technical discussion and a chance to ask questions you have about the project idea, QEMU, and GSoC. The coding exercise is designed to show fluency in C programming.

Here is a C coding exercise we have used in previous years when interviewing students: 2014 coding exercise

Try it and see if you are comfortable enough writing C. We cannot answer questions about the previous coding exercise but hopefully it should be self-explanatory.

If you find the exercise challenging, think about applying to other organizations where you have a stronger technical background and will be more competitive compared with other candidates.

Find Us

  • IRC (GSoC specific): #qemu-gsoc on irc.oftc.net
  • IRC (development):
    • QEMU: #qemu on irc.oftc.net
    • libvirt: #virt on irc.oftc.net
    • KVM: #kvm on chat.freenode.net

Please contact the mentor for the project idea you are interested in. IRC is usually the quickest way to get an answer.

For general questions about QEMU in GSoC, please contact the following people:

Project Ideas

This is the listing of suggested project ideas. Students are free to suggest their own projects, see #How to propose a custom project idea below.

QEMU audio backend

Summary: Rework QEMU audio backend

The audio backend facilitates audio playback and capture using host audio APIs (CoreAudio, PulseAudio, DirectSound, etc). It is used by emulated soundcards and may need to convert between the audio format supported by the emulated soundcard and the format supported by the physical soundcard. This area of the codebase has been stable for a long time but is now due some significant improvements.

The goal of this summer project is to improve the audio/ backend. The preliminary task is to rebase and merge (some or all) of the GSOC "audio 5.1 patches 00/51" series which modernizes the audio backend codebase.

Then, add a generic GStreamer audio backend. GStreamer is an open source multimedia framework that is cross-platform and already supports a lot of the functionality that is implemented in QEMU's audio backend.

Finally, try to replace as much of audio/ by custom gstreamer pipelines. This would be a major simplification that reduces the code size significantly, making QEMU's audio backend smaller and easier to maintain.

Links:

Details:

  • Skill level: intermediate or advanced
  • Language: C
  • Mentors: marcandre.lureau@redhat.com, kraxel@redhat.com
  • Contact: past gsoc student "Kővágó Zoltán" <dirty.ice.hu@gmail.com>
  • Suggested by: marcandre.lureau@redhat.com

Disk Backup Tool

Summary: Write a tool that performs both full and incremental disk backups

QEMU has added command primitives that can be combined to perform both full and incremental disk backups while the virtual machine is running. A full backup copies the entire contents of the disk. An incremental backup copies only regions that have been modified. Orchestrating a multi-disk backup to local or remote storage is non-trivial and there is no example code showing how to do it from start to finish.

It would be helpful to have a "reference implementation" that performs backups using QEMU's QMP commands. Backup software and management stack developers wishing to add QEMU backup support could look at this tool's code as an example. Users who run QEMU directly could us this tool as their backup software.

You need to be able to read C since that's what most of QEMU is written in. This project will expose you to backup and data recovery, as well as developing command-line tools in Python.

See the links to familiarize yourself with disk image files, backups, and snapshots.

Links:

Details:

  • Skill level: intermediate
  • Language: Python
  • Mentors: John Snow <jsnow@redhat.com> (jsnow on IRC), Stefan Hajnoczi <stefanha@redhat.com> (stefanha on IRC)

Moving I/O throttling and write notifiers into block filter drivers

Summary: Refactor the block layer so that I/O throttling and write notifiers are implemented as block filter drivers instead of being hardcoded into the core code

QEMU's block layer handles I/O to disk image files and now supports flexible configuration through a "BlockDriverState graph". Block drivers can be inserted or removed from the graph to modify how I/O requests are processed.

Block drivers implement read and write functions (among other things). Typically they access a file or network storage but some block drivers perform other jobs like data encryption. These block drivers are called "filter" drivers because they process I/O requests but ultimately forward requests to the file format and protocol drivers in the leaf nodes of the graph.

I/O throttling (rate-limiting the guest's disk I/O) and write notifiers (used to implement backup) are currently hardcoded into the block layer's core code. The goal of this project is to extract this functionality into filter drivers that are inserted into the graph only when a feature is needed. This makes the block layer more modular and reuses the block driver abstraction that is already present.

This project will expose you to QEMU's block layer. It requires refactoring existing code for which there is already some test coverage to aid you.

Links:

Details:

  • Skill level: intermediate
  • Language: C
  • Mentor: Kevin Wolf <kwolf@redhat.com> (kwolf on IRC), Stefan Hajnoczi <stefanha@redhat.com> (stefanha on IRC), Alberto Garcia (berto on IRC)

PCI Express to PCI bridge

Summary: Code an emulated PCIe-to-PCI bridge for QEMU PCI Express machines

Modern Virtual Machines and their devices are PCI Express, however a means of supporting existing PCI and PCI-X deployment is required. Some use cases may need using legacy PCI devices that plug into platforms that exclusively support PCI and PCI-X system slots.

QEMU already has a solution, the i82801b11 DMI-to-PCI Bridge Emulation. However, the device has some disadvantages: it cannot be used by ARM guests and it is part of the Root Complex, so it can't be hot-plugged.

The goal of this summer project is to code a generic PCIe-PCI bridge. The bridge should be hot-pluggable into PCI Express Root Ports and be usable across various architectures and Guest Operating Systems.

Once the bridge is merged upstream, the PCI/PCI Express infrastructure will be ported to the QOM model to conform with QEMU standards, all that as the time permits.

Links:

Details:

  • Skill level: intermediate
  • Language: C
  • Mentor: marcel@redhat.com, marcel_a on IRC
  • Suggested by: Marcel Apfelbaum <marcel@redhat.com>

Add a Hypervisor.framework accelerator

Summary: Add x86 virtualization support on macOS using Hypervisor.framework

QEMU does not yet take advantage of Hypervisor.framework, the API for hypervisors on macOS. Currently one must use the slower TCG just-in-time compiler or the Intel HAXM accelerator module that relies on a third-party driver.

Hypervisor.framework was added to macOS in Yosemite (10.10). It exposes the Intel VMX CPU feature for running guest code safely at native speed. The main difference to the KVM or HAXM APIs is that the Hypervisor.framework user must implement instruction emulation to handle instructions that vmexit due to I/O accesses. Most of the code will be related to this emulator.

QEMU would be able to run x86 virtual machines with much better performance and without relying on third-party drivers thanks to Hypervisor.framework. This will make QEMU more useful on macOS and encourage more contributions from developers on that platform.

This project is an advanced project. You should be familiar with the concept of an emulator. Luckily there is the Linux KVM code as well as other code that implements VMX or Hypervisor.framework to use for inspiration. You will learn about writing the most core part of a hypervisor.

There is an existing QEMU-based Hypervisor.framework implementation in Veertu's hypervisor. This can serve as a reference and one way to approach the project is to take that code and get it merged into QEMU after necessary changes have been made.

Links:

Details:

  • Skill level: advanced
  • Language: C
  • Mentor: Alexander Graf <agraf@suse.de>

Python module for Jailhouse

Summary: Factor out a Python module for the Jailhouse command & control interface

The partitioning hypervisor Jailhouse is controlled from a Linux guest system (the root cell) via a command line tool (jailhouse). This tool consists of a small core written in C, providing the minimally required services to operate the hypervisor. For more advanced features like configuration file generation or the loading of additional Linux guests, a set of extension scripts have been written in Python. The scripts are now at a point where they would benefit from using a "pyjailhouse" module that should implements common functionality only once, e.g. configuration format or system information parsing but also interaction with the low-level hypervisor control interface.

The goal of this project is to create such Python module, transfer existing code from the scripts into it, and make sure that the module is both properly installed and also usable from the source directory. As a reuse case and benchmark for a reasonable split-up, jailhouse hardware check shall be enabled to parse the system configuration itself, instead of relying on a config file previously generated by jailhouse config create.

Bonus (with advanced Python experience): Further refactoring of the system configuration parser and config file generator to enable the reuse on non-x86 architectures or for generating and validating non-root cell configurations.

Links:

Details:

  • Skill level: intermediate to advanced
  • Language: Python (basic C knowledge helpful)
  • Mentors: Jan Kiszka <jan.kiszka@web.de>, Valentine Sinitsyn <valentine.sinitsyn@gmail.com>

New configuration format for Jailhouse

Summary: Define a new Jailhouse configuration source file format and implement a compiler for it

So far, the configuration files for the Jailhouse hypervisor are defined in C by filling structures and array and then translated into their binary representation via standard gcc. In order to simplify the error-prone definition process while keeping the binary output format unchanged, a new source form shall be developed. That could be YAML-based, but alternatives can be discussed as well.

The requirements on the format are

  • human readability (no XML...)
  • easily modifiable by humans (e.g. by using symbolic labels for references, instead of array indexes)
  • unambitious transformation into binary format
  • optional: support for including or referencing common fragments (e.g. device resources initially used by root cell, then transferred to a non-root cell)
  • optional: support for grouping of associated resources (e.g. a PCI device with its capabilities and memory regions)

In order to use the format in place of the existing C descriptions, a compiler shall be written (can be in Python, C or a mixture) to generate the binary representation of the configuration files and hooked into the Jailhouse build process. There will surely be a transitional phase before the new format is matured and old format can be discontinued. This phase will likely last longer than this project.

Links:

Details:

  • Skill level: advanced
  • Language: Python, C
  • Mentors: Jan Kiszka <jan.kiszka@web.de>, Valentine Sinitsyn <valentine.sinitsyn@gmail.com>

Project idea template

=== TITLE ===
 
 '''Summary:''' Short description of the project
 
 Detailed description of the project.
 
 '''Links:'''
 * Wiki links to relevant material
 * External links to mailing lists or web sites
 
 '''Details:'''
 * Skill level: beginner or intermediate or advanced
 * Language: C
 * Mentor: Email address and IRC nick
 * Suggested by: Person who suggested the idea

How to propose a custom project idea

Applicants are welcome to propose their own project ideas. The process is as follows:

  1. Email your project idea to qemu-devel@nongnu.org. CC Stefan Hajnoczi <stefanha@gmail.com> and regular QEMU contributors who you think might be interested in mentoring.
  2. If a mentor is willing to take on the project idea, work with them to fill out the "Project idea template" above and email Stefan Hajnoczi <stefanha@gmail.com>.
  3. Stefan will add the project idea to the wiki.

Note that other candidates can apply for newly added project ideas. This ensures that custom project ideas are fair and open.

How to get familiar with our software

See what people are developing and talking about on the mailing lists:

Grab the source code or browse it:

Build QEMU and run it: QEMU on Linux Hosts

Important links

Information for mentors

Mentors are responsible for keeping in touch with their student and assessing the student's progress. GSoC has a mid-term evaluation and a final evaluation where both the mentor and student assess each other.

The mentor typically gives advice, reviews the student's code, and has regular communication with the student to ensure progress is being made.

Being a mentor is a significant time commitment, plan for 5 hours per week. Make sure you can make this commitment because backing out during the summer will affect the student's experience.

The mentor chooses their student by reviewing student application forms and conducting IRC interviews with candidates. Depending on the number of candidates, this can be time-consuming in itself. Choosing the right student is critical so that both the mentor and the student can have a successful experience.

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