From owner-freebsd-hackers  Wed Jun  4 10:29:09 1997
Return-Path: <owner-hackers>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id KAA12059
          for hackers-outgoing; Wed, 4 Jun 1997 10:29:09 -0700 (PDT)
Received: from george.lbl.gov (george-2.lbl.gov [131.243.2.12])
          by hub.freebsd.org (8.8.5/8.8.5) with SMTP id KAA12048
          for <freebsd-hackers@FreeBSD.ORG>; Wed, 4 Jun 1997 10:29:07 -0700 (PDT)
Received: from localhost (peb@localhost) by george.lbl.gov (8.6.10/8.6.5) with SMTP id KAA04850 for <freebsd-hackers@FreeBSD.ORG>; Wed, 4 Jun 1997 10:29:07 -0700
Date: Wed, 4 Jun 1997 10:29:06 -0700 (PDT)
From: Pat Bozeman <peb@george.lbl.gov>
Reply-To: PBozeman@lbl.gov
To: freebsd-hackers@FreeBSD.ORG
Subject: Re: Virtual address question for VM guru's 
In-Reply-To: <199706040745.RAA16094@ogre.dtir.qld.gov.au>
Message-ID: <Pine.SOL.3.95.970604100035.1799F-100000@george.lbl.gov>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-hackers@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk


Thanks to all for the input, here is what I propose to do, if this doesn't
make sense can someone please correct me (although I understand the
general ideas behind the FreeBSD VM system, I don't really have a good
handle on the details of the implementation so this may not quite make
sense)

fault in and wire all pages in user supplied buffer (already working)

build vm_page_t ms[] of pages in buffer
get a new kva by calling kmem_alloc_pageable(kernel_map, buffer_size)
associate buffer pages with kva by calling pmap_qenter(kva, ms, npages)

My understanding is that kmem_alloc_pagable allocates virutal addresses
that do not have coresponding physical addresses.  Then, pmap_qenter takes
the new virtual address and associates n pages starting at that address
with the physical addresses of the vm_page_t array.