Re: Time to fix the memory allocation on port-amiga

["Michael L. Hitch" <mhitch%gemini.msu.montana.edu@localhost>]

On Thu, 23 Dec 2010, Ignatios Souvatzis wrote:

> You'll probably have to rewrite the pmap code in the kernel. The
> old one could only handle a limited amount of kernel virtual
> memory - which is also needed to hold the page tables for user
> processes, which can be huge for X-servers operating on more
> modern graphics cards.
>
> The old pmap only had a limited amount of 2nd level descriptors;
> fitting into one 8k page, and leaving one for the first level.

  That limitation is for user pmaps only - the kernel can allocate as much
contiguous memory for the segment tables as desired.  I've not seen the
kernel even approach the number that the current pmap can use.  There was
an option in the amiga pmap that was used to increase that, but the common
pmap_motorola.c does not have that option, and if I remember correctly, it
allocate quite a few more pages that the amiga pmap did.

Mike