MorphOS Developer
Posts: 1520 from 2003/2/24
From: Finland
Quote:
Cego wrote:
What is flat shared?
Flat: continuous memory (not segmented) which can be addressed by single integer starting from 0 to 4GB minus one. (Does not matter on Amiga, this is just x86 mumbo jumbo.)
Shared: there is single 4GB address space divided to IO, kernel, VRAM and RAM or virtual RAM. All remaining address space that is not used by others (IO, kernel, VRAM) can be used by RAM or virtual RAM. On G5 there is 1GB remaining and if you have 1GB RAM there is nothing left to virtual RAM. If you had 512 MB RAM only then there would be another 512 MB available to virtual memory but it is better have 1 GB RAM at once.
Quote:
And would it be possible to use something else?
By using isolated address spaces the system could use more physical RAM. This solution is not backward compatible.
Or reduce space used by IO, kernel and VRAM but how it works is beyond my knowledge.
Or switch to full 64-bit addressing but it is not backward compatible and not going to happen on PPC.
(I hope I am not completely wrong... :)
1 + 1 = 3 with very large values of 1