On 2018-03-30 22:31, Joerg Sonnenberger wrote:
On Fri, Mar 30, 2018 at 04:22:29PM -0400, Mouse wrote:And I (and ragge, I think it was) misspoke. It doesn't quite require 128K of contiguous physical space. It needs two 64K blocks of physically contiguous space, both within the block that maps system space. (Nothing says that P0 PTEs have to be anywhere near P1 PTEs in system virtual space, but they do have to be within system space.)...and the problem to be solved here is that the memory has become fragmented enough that you can't find 64KB of contiguous pages? If so, what about having a fixed set of emergency reservations and copying the non-contiguous pmap content into that during context switch?
I don't think that was Ragge's problem.The problem was/is (if I understood it right), that someone can mmap more than 1G, and that will never be possible to map on the VAX. The P0 space is only 1G, and the same is true for the P1 space. But P0 and P1 is disjunct, so don't try to think of them as contiguous space.
So, anything trying to grab more than 1G will never be possible. But it would appear that the MI part don't give any hooks to stop a process from going just that.
Johnny
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