sunday, 9 march 2008

posted at 09:24
tags:

I started writing a long post about what I'm working on right now, but its really quite disjointed because I realised I don't actually have a point to make. So here's the short version of what I've been doing this week.

To be really useful, WebKit needs to be a shared library. On AROS, we can't support this in the normal way because of issues with global variables. The solution involves large-scale changes to the program loader and execution code.

AROS executables are actually ELF relocatable objects rather than executable objects. This is done so we can relocate programs on the fly without needing a MMU. To implement ELF shared libraries properly though, we need the extra information provided by ELF executables as they contain (among other things) the dependency list.

What I'm doing is to make AROS executables be ELF shared objects, containing both the relocation information and the dependency list, as well as other stuff. This requires a new loader for this object type, but I'm taking the opportunity to merge the existing ELF loaders since there's a lot of overlap of functionality.

Once shared object "executables" are available, I can begin implementing the library side of things. These are essentially the same thing, except that they will be position-independent, and so the loader will have to deal with setting up the GOT and PLT. The tricky bit arranging for each instance of the library to find its GOT. I'm still wrapping my head around that.

Once thats done, we'll be able to Unix-style .so libraries in addition to our standard ones. Not long after, we'll have a properly-sharable WebKit.zcc, with pretty things like libcairo.so and so forth.

I'll post more as I have time, progress and proper brain to describe it.