Subject: Re: Some VAX pmap observations
To: Anders Magnusson <ragge@ludd.luth.se>
From: Jason R Thorpe <thorpej@wasabisystems.com>
List: port-vax
Date: 04/29/2002 10:31:18
On Mon, Apr 29, 2002 at 07:21:12PM +0200, Anders Magnusson wrote:
> pmap_enter() enter pages with the valid bit not set in the pte to be
> able to simulate the non-existing reference bit. The kernel stack is
> not legal to have invalid, therefore the valid bit must be set in
> each pte.
But when pmap_enter() is called to wire the kernel stack, it should be
called with an access type (in the flags argument) of VM_PROT_READ |
VM_PROT_WRITE. You can use this informat to seed the "referenced" emulation
and immediately set the valid bits in the PTEs.
...in fact, it looks like it does this already :-)
> Due to a recent change (some year ago or so) the valid bit in the pte
> is already set in pmap_enter() on wired pages, so this small loop can
> probably be removed :-)
Ah, indeed :-)
--
-- Jason R. Thorpe <thorpej@wasabisystems.com>