Glendix: The Why and the How

Glendix is a Linux distribution with a Plan 9 userspace. This presentation goes over the main motivation behind the project and shares some implementation decisions.

Transcript

1. A Plan9/Linux Distribution Anant Narayanan Vrije Universiteit, Amsterdam IWP9 2008 Glendix
2. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 What? • Providing a Plan 9 development environment on Linux • Providing the ability to run Plan 9 applications on Linux as a side effect
3. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 Why? • Spread the message of Plan 9 style programming to Linux developers • Experience the benefits of Plan 9 applications along with the convenience of being able to execute Linux applications • Because we can: Linux isn’t inherently tied to any particular user-space :-)
4. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 How? • Stage 1 • Binary format loader for a.out (module) • Implementation of the Plan 9 system calls (patch)
5. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 How? • Stage 1I • Implement synthetic filesystems that applications depend on (v9fs or kernel patch depending on specifics)
6. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 How? • The idea is to trick applications into thinking that they are, in fact, running on a Plan 9 kernel
7. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 Binary Loader • Fairly straightforward • Except for the padding and tos issues • Solved by assigning different magic numbers to padded and non-padded executables and using Linux’s interpreter execution capabilities to modify executable
8. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 System Calls • Fall into three categories • Trivial: Minor modifications to existing Linux calls (open, read, write) • Easy to Implement: Not present, but can be written relatively easily (fd2path) • Tricky: Needs data-structure level changes and low-level kernel code (rfork, bind)
9. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 Filesystems • /net and /dev/draw are the two major ones we are focussing on • /net is relatively easy, maps to internal networking calls • /dev/draw is harder because of the need to support graphics cards • Debate over whether to use kernel framebuffer or DirectFB
10. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 When? • Stage I: 60% complete • Stage II in planning phase • 24 of 51 system calls implemented • Major milestone: 8c/8l
11. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 9vx & Glendix • 9vx is x86-only. While Glendix is also x86- only for now, easily extendable • Different purposes: In Glendix, executables are not run in a “sandbox” - rather as any regular user-space application • Glendix aims for a more low-level, comprehensive integration of Plan 9 & Linux
12. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 Q & A
13. 3rd International Workshop on Plan 9 Volos, Greece 30 October, 2008 Thank You! http://glendix.org/ anant@glendix.org