Re: mmap implementation advice needed.

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Fri, Mar 30, 2018 at 01:10:37PM -0400, Mouse wrote:
> It takes 4 bytes of PTE to map 512 bytes of VA.  (The VAX uses the
> small, by today's standards, page size of 512 bytes.)  So 2G of
> userland space requires 16M of PTEs.  Those PTEs must be in system
> virtual space.  And that 16M of system virtual space requires 128K of
> PTEs to map, and _those_ PTEs require contiguous physical space.

Let me try to rephrase that:

The first level page table of VAX needs up to 128K (for each of the two
ranges?) as contiguous physical space.
The second level page table needs 16M in some block size, but they don't
need to be all contigously?

Joerg