> The problem is the parts of the kernel page table that must map the
> user page tables, that must be in physical contiguous memory and
> therefore allocated at boot.

I must be missing something.

Mapping 128M of user space requires 1M of user page tables in kernel
virtual space; mapping 1M of kernel virtual space requires 8K of
(physically contiguous) kernel page tables.

This doesn't sound too bad - especially since many of those pages of
user PTEs will usually be identical no-access pages that could be
collapsed (though I think I saw someone say that the VAX pmap doesn't).
Is the pmap statically allocating MAXPROC times this 8K of space or
something?

Also, do we support the KA620?  If so, I could see trouble finding
physically contiguous space for the user page tables, but the VAX
supported hardware list doesn't include the KA620 as far as I can see.

					der Mouse

			       mouse@rodents.montreal.qc.ca
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