Voyager

Documentation

IBM Redbooks

• SG24-4630-00 OS/2 Warp (PowerPC Edition) A First Look
• SG24-4639-00 OS/2 Warp (PowerPC Edition) Graphical Subsystem

We do have the first one digitaly, but not the second one. In case anyone finds that, let us know.

Darwin Documentation

There is plenty of documentation available about Darwin, a good start is Kernel Programming, which gives a nice overview about the design of the kernel.

Technologies to study

• OpenGL, FreeGLUT, CPW (Application framework for windows, menus etc.). Here's a Readme text.
• glitz - OpenGL interface for Cairo, so one could run Cairo directly on OpenGL, see Xegl for a diagram.
• Glitz: Hardware Accelerated Image Compositing Using OpenGL and as PDF
• The State of Linux Graphics, comments and more comments
• Current gtk+ development- among other topics about cairo integration and a new theme system
• X on GL states very clearly, what has still to be done
• DirectFB with rootless XServer, hardware accelerated OpenGL, GTK+ backend, an experimental Cairo backend, Qt backend, DirectVNC, SDL backend
• Enlightenment and its support libs. Here's a Live CD.
  • Why Englightenment? So far I just knew it as a fancy desktop, what makes it special? Ktk 15:39, 30 October 2005 (CET)
  • Cinc: it's more than just a fancy desktop. It offers quite some libs e.g. HW accelerated canvas on top of OpenGL, libs for alphachannel blending of pics, antialiased text, imlib and quite some more.
• GNUstep.org

Design Decisions

Creating a binary compatible OS/2 clone may be tempting but is not strictly necessary. Important is the user experience. Which toolkit should be used for primary development?

Graphics Drivers

• X11
• OpenGL ES (an OpenGL only desktop)
• DirectFB
• SciTech Snap Graphics

These graphics engines can be emulated vice-versa: You can run X11, OpenGL, and DirectFB programs on the same graphics driver. We should have a look at HW support when chosing the driver system. For example I've read OpenGL drivers are not that common (often they're not HW accelerated). A viable idea may be to just use OpenGL as the core API on top of something else. There're quite a lot OpenGL implementations running on different low level drivers or even Mesa.

2D API

• Cairo. Cairo has a PDF-like engine which seems to be inspired by Quartz of MacOS X.
• Cairo runs on almost everything, including OS/2 and X but also directly on OpenGL hardware with Glitz. So one could use it as a complete GPI replacement without the need of X one day.
• To make things easier 24Bit screens should be the primary target. Hell it's 2005 today...

It seems there are many possiblities here!

• General Graphics Interface
• Cairo (used by GTK+)
• Evas (used by Enlightenment)
• libart (used by Gnome)
• Anti-Grain Geometry
• Simple DirectMedia Layer
• Arthur (used by KDE)

We will have to use more than one. KDE programs use Arthur, GTK+ ones use Cairo, and so on ... These libraries are (mostly) used for display and printing. So we won't have a consistent graphical subsystem with this multitude.

All these libraries have several backends, e.g. X11, DirectFB, OpenGL, OS/2, ...

Even if we do have to use more than one we should focus on a library that is widly supported, at the moment my impression is that Cairo will win the race. Mozilla is using it for new versions, OOo will use it and GTK+ is migrating into it as well. Also projects like Glitz will dramatically speedup the rendering in the Cairo engine. See some comments of one of the GTK+ developers.

MM

• The concept of IO procedures should be retained at least for file IO and format converting.

Toolkits

• GTK+
• GnuStep (look at Apples programs to see what's possible. Yes I know Apple uses Cocoa not Gnustep)
• other?

SOM

Dropping SOM for something better? Creating a poor mans SOM kernel isn't too difficult (Cinc: there's already a working prototype for the basic functionality).

If SOM is dropped, no binary compatibility for old WPS enhancements is given. This may break a considerable amount of OS/2 apps. This may not be an issue if applications have to be recompiled anyway for a new plattform. Cinc: I don't see many OS/2-apps which are worth to be supported no matter how much work it needs. Binary compatibility is out of sight IMHO. Nobody really needs it (anyone really using OD nowadays?).

WPS

• The WPS should be designed with REXX scriptability in mind (like WPS-wizard addon)

REXX

• REXX should be implemented like AppleScript so controlling of applications from other apps is possible (commands not tied to one process).
• Regina may be used as an interpreter.
• any REXX replacement should implement the following
  • true CMD integration like under OS/2
    • access to environment vars of the calling interpreter. Cinc: ???
  • support of the full REXX C API or an equivalent concept (macro space control, app handlers, WPS object access API etc). Most of this is supported by Regina AFAIK.
  • complete reimplementation of REXXUTIL ! I seem to remember having seen such a project for Windows and Unix.

Backward Compatibility

The question about backward compatibility is indeed a good one, it's risky to break with the current OS/2 API for religious reasons but one should have a look at that more from a technical point of view. The OS/2 API is not really modern anymore, programming directly on PM is much more work than using a modern toolkit like GTK+.

At the moment it's unfortunately unlikely that PM and WPS source get released by IBM.

Options:

• implement parts of PM and GPI on top of the new 2D API and try to integrate it with the toolkit choosen (same look & feel, clipboard support, D&D, etc. That's a lot of work, the question is if this is really necessary. We would have to do the same for supporting other toolkits like qt (which is a requirement).
• Implement only some crucial parts to ease source code migration. For example message queues, concept of object windows (often used to comunicate with background threads).
• Map often used PM-functions to counterparts of the chosen toolkit.
• Use a VM and run OS/2 or eCS inside the VM. There are very promising opensource VMs like
  • XEN
  • QEMU

XEN seems to be the most promising one at the moment because it will support dual core CPUs in the future so one can run the guest OS on a separate CPU core. So far one had to alter the guest OS in sourcecode but that changes at the moment because they integrate parts of QEMU sourcecode inside XEN to emulate those parts (memory allocation and such stuff).

Questions

• the Xegl diagram mentioned above only shows the path of the graphics; the path of e.g. mouse and keyboard input is missing; that's not as trivial as it sounds (it has been missing in Xegl, when that was stopped); will we use OS/2-like driver model or wait for x.org 7.0 (currently RC1!) and take out the input system from there? Other sources (hotplug, ...)?
• one good thing about OS/2 are the fast interactions when you click somewhere, like opening a folder or getting the focus on a window. Why is that like this? We should try to keep that stuff fast.
• do we want the traditional window manager<->application scheme? With the Gnome/KDE interfaces? Then we are deep in X again ...
  • the question is if we can incooperate the WM functionality in GTK somehow. As far as I remember Fresco implemented GTK API as well so one might have a look at that.
  • IMO GTK runs on top of a WM. The WM just gives GTK a surface to work with but manages where on screen this surface will be painted. Even OS/2 has something like a WM managing the windows for us.