On the move

The project is going forward steadily and while we're still merging, some things are already moving forward again.

One of them is the paging subsystem. Well, actually it's gone backwards but that's mainly because it's a rewrite (can't clean up without making a mess first).

One thing I'm working on is getting the pages to be put in the page tables to be put in a page directory (yes, Intel couldn't make it simpler).

That's not really my issue here, but what is my issue is that I have to find out a way to get the pages to be marked free and used, without requiring 4MiB as I used to.

I have got some designs ready, one of which is the old design, which was underwhelming to say the least. Another is a simple bitmap, with the processes maintaining their own page locations. The last one is to have a list of regions, which is a doubly linked list so the processes can also mark the pages as used for them selves. This does however put me at a 8MiB max. The sunny side, however is that there also is an 8 byte minimum, and that with a bit of work, the fragmentation could be resolved, to make the entire requirements just a bit smaller.

Now this 8 MiB max is only on 32-bits systems, as on 64-bits this can be doubled. The bitmap approach has got several advantages, one of which is that it's small and easy to maintain. That is until we're going to think about swapping pages out to disk. At that moment, all hell breaks loose, and code is flying around randomly.

So my choice is this: "Am I going for low memory usage, easy swapping or easy maintenance?" You'll hear the answer soon (hopefully).