Shell & Display Next hackfest

Brno, 24-26 April inclusive

Primary contact: Carlos Soriano Sanchez <>
Secondary contact: Tomas Popela <>

Relevant GNOME team

Shell & mutter, possibly Design. Teams outside of GNOME will be key too, for KMS/DRM, Mesa, etc.


Planning and development of the technical infrastructure for various features for display-next technologies, specifically those that need GNOME Shell to work in tandem with the GPU stack. One of the main examples of this is HDR support.

This hackfest intends to put together engineers across the display/GPU stack, including folks from freedesktop and the upstream kernel. It's a great opportunity for GNOMErs to meet and collaborate with members of other communities.

The proposed length of the hackfest is 2 full days and a third day for wrapping up during the morning and doing some local activity during the afternoon.

Agenda, goals

Goals The main goal is to plan the next 1-2 years of work and direction in how to support HDR, VRR and other new GPU and graphics technologies that are exposed to the final user through Mutter and Shell.

In addition, the second main goal is to discuss, plan and agree on how to improve KMS and Wayland APIs to better accommodate user space needs for these technologies, specially necessary for HDR.

The third main but optional goal is for the UXD team to discuss the next iteration of Shell designs, and expose their needs to the GPU, graphics and Shell/Mutter engineers to gather feedback on what's feasible and what APIs would be necessary.


  • HDR - Leads: Jonas, Sebastian, Benjamin
    • HDR modes (PQ, HLG, SBTM, and Metadata)
    • Approaches for compositing SDR, color managed SDR and HDR
      • ICC workflow
      • Implicit color managed workflow
      • Gamut and tone mapping
      • Linear spaces for blending, scaling
    • Viewing environment adjustment
      • Brightness/backlight adjustment
      • PQ absolute luminance TF
      • Tone mapping
    • Mutter and GTK roadmap
    • Wayland color-representation and color-management protocols
    • HDR UX (Settings, enabling and disabling HDR, power considerations, etc)
    • Dynamic Metadata support
  • VRR - Leads: Manasi, Michel
    • State of the art
    • Addressing apps bogging down Mutter
  • KMS properties – Leads: Sebastian, $ANYONE?
    • More control over the connector
      • Min/Max BPC
      • YCC support and subsampling
      • Colorspace
      • Compression (DSC)
      • Broadcast RGB, Limited/Full range handling
    • The KMS Color Pipeline
      • Continuing XDC HDR talk/workshop (Harry)
      • How to offload color transformations to the display controller
    • Backlight control (Hans De Goede?)
    • EDID/DisplayID/DDCCI
  • Direct scanout on non-compositing GPUs - Leads: Michel, Jonas
    • NVIDIA Advanced Optimus equivalency
    • Use cases and possible gains
    • Missing pieces - KMS APIs, Mutter, driver support, etc.
    • Coming up with a roadmap
  • UXD - Leads: AllanDay, JakubSteiner, TobiasBernard

    • Optional, potential separate track to the rest of the event
    • We have a number of shell design topics on the backlog, though whether we’ll be in a position to tackle these in the autumn is unclear

Code of Conduct

As for all GNOME-related events, the GNOME Events Code of Conduct and CodeOfConduct/PhotographyPolicy apply.

Any violations of either should be submitted to the event organizers (see above) or the GNOME Code of Conduct Committee


  • 1st day: attendees arrive
  • 2nd day: plan work and do some work
  • 3rd day: do more work
  • 4th day: wrap up during the morning, sponsored activity (TBD) by Red Hat during the afternoon.


Red Hat will sponsor the Venue and Red Hatters accommodation and travel attending. Additionally, Red Hat will sponsor a small activity (TBD) during the afternoon of the last day for everyone attending.

Possible Attendees


Relevant contribution/aim

Arrives on

Departs on

Staying at

Confirmed attendance

Michel Daenzer

Red Hat - full GPU stack: drm/kms, VRR, Mesa


Niels de Graef

Red Hat - GPU team PO for HDR


Hans de Goede

Red Hat - Kernel client development



Sebastian Wick

Red Hat - HDR full stack developer

Jonas Adahl

Red Hat - Mutter maintainer

Carlos Soriano

Red Hat - logistics and Red Hat GPU team coordination





Allan Day

Red Hat - UXD

Benjamin Otte

Red Hat - GTK GL/color mgmt work with Sebastian, synchronizing client and compositor-side needs and technologies

Carlos Garnacho

Red Hat - Mutter maintainer

Florian Muellner

Red Hat - Shell maintainer

Robert Mader

Collabora - YUV support and firefox graphics related work

Alexander Goins


Pekka Paalanen (pq)

Wayland/Weston maintainer, parts of CM&HDR protocol design and Weston implementation, color-and-hdr




Marco Trevisan

Canonical - Shell and Mutter contributor


Jesus Soto


Melissa Wen

Igalia - KMS CRTC 3D LUT

Georges Basiel Stavracas Neto

Endless - Mutter/GNOME Shell maintainer

Sharma Shashank

AMD - HDR on Linux (Intel-display/I915 + Weston/Kodi)

Jiri Koten

Red Hat - Desktop PO

Harry Wentland

AMD - exposing per plane color

Tobias Bernard

Purism - UXD

Jakub Steiner

Red Hat - Pixel Pushing

Manasi Navare

Intel - leading kernel development of DSC and VRR at Intel

Additional possible key attendees (add your name in the table above for confirming interest in attendance and edit your relevant contribution)


Relevant contribution/aim

Ville Syrjala

Intel kernel display developer

Daniel Vetter

Intel DRM maintainer

Dor Askayo

VRR contributor

Uma Shankar

Intel - exposing per plane color (cannot attend)

Simon Ser

SourceHut/Valve - Wayland/Mesa

Hans-Kristian Arntzen

Valve - vkd3d-proton (pointed to Josh Ashton)

Pierre-Loup A. Griffais

Valve (pointed to Josh Ashton)

Josh Ashton

Valve - HDR on gamescope (cannot attend, possibly remotely)

David Edmudson

KDE - color/HDR

Vlad Zahorodnii


Xaver Hugl



One good option for accommodation close to the venue is: Hotel Vista - which is about €70 night.

Flights from EU around €200 to either Vienna or Prague. Then Student Agency train from any of those cities to Brno around €12.

How to get there

From Europe or faraway places

  • Fly to Vienna or Prague airport
  • Direct bus from the airport bus stations to Brno through Reservation required in advance through that website.

  • Alternatively, train from those cities to Brno through too.

    • From Vienna airport, you will need to take a regular train to Vienna hbf (main train station a.k.a. hauptbahnhof). The regular train goes every 20 min aprox and tickets can be bought in the Vienna airport machines directly and takes around 30 min travel. Then you can take the Student Agency train to Brno from VIenna hbf.
    • From Prague, you can take a bus to the main train station (a.k.a. Hlavni Nadrazi) through regular city buses in the Prague airport. A ticket can be bought in the yellow colored machines directly in the bus stations of the airport (Czech crown coins required I believe).


Red Hat offices, TPB-B. Hosted in the 1st floor, in the Plutonium and Selenium rooms.

You can get to the venue by tram number 12 from the center in "Ceska" tram stop as well as from the main train station "Hlavni Nadrazi", direction Technologicke Park. You can use the PubTram android and ios app to get times for the trams (every 7 min).

Accommodation and food


QWERTY, Map - 5 min walking from the venue. Relatively small place with lighter Czech food.

Chilli Tree, Map - Reasonable quality and priced Thai food, including vegetarian and vegan options.

Forky's - Excellent modern vegan restaurant in the center. 20 min tram trip from the Venue.


One good option is: Hotel Vista - map - The best way to get to the venue from this hotel is taking bus number 65 in tram stop "Vozovna Medlánky" direction "Technologický park" and get out in the last stop, named "Technologický park", for a total of 7 min. Walking is about 15 min. - directions to the venue.

Previous discussions, organization threads, drafts, relevant links, etc

(!) <list of any resource like mailing lists, forums, wiki pages, etc where this has been discussed so far>

(!) Note to organizers
it is expected that you have contacted relevant teams or groups for your hackfest prior to proposing it, for example if you plan to do an Art hackfest, contact the Art team for ideas.


Hackfests/ShellDisplayNext2023 (last edited 2023-01-26 13:51:44 by HansdeGoede)