[coyotos-dev] Fixing the kernel heap size

[Jonathan S. Shapiro]

On Thu, 2007-12-20 at 06:25 -0500, Godfrey Vassallo wrote:
> Charles Landau's suggestion to question the "struct Page" object
> relative to device memory is worth consideration. Is it possible to
> store a much larger page size in the struct and to compute the tlb
> data required? At first blush that may be workable for s/w managed
> tlb's but will present a problem for h/w managed tlb's. 

This is an interesting point. It's not a problem for h/w managed TLBs
either. Here are the requirements:

1. Page size must be a power of two.
2. Page size must be <= basic system page size.
3. Whatever page size you choose, that becomes the least unit of
   sharing.  Hmm. That may not be correct. I need to think about that
   one.

So the issue with larger page sizes for devices is mainly that they
constrain the use of shared mappings to larger units.

Godfrey, I think you have made an interesting and provocative point
here.


shap