From owner-freebsd-fs Sat Jun 9 12:36:40 2001 Delivered-To: freebsd-fs@freebsd.org Received: from peter3.wemm.org (c1315225-a.plstn1.sfba.home.com [65.0.135.147]) by hub.freebsd.org (Postfix) with ESMTP id 36A9C37B401; Sat, 9 Jun 2001 12:36:31 -0700 (PDT) (envelope-from peter@wemm.org) Received: from overcee.netplex.com.au (overcee.wemm.org [10.0.0.3]) by peter3.wemm.org (8.11.0/8.11.0) with ESMTP id f59JaVM65605; Sat, 9 Jun 2001 12:36:31 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by overcee.netplex.com.au (Postfix) with ESMTP id E5EE9380C; Sat, 9 Jun 2001 12:36:30 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.3.1 01/18/2001 with nmh-1.0.4 To: tlambert2@mindspring.com Cc: "Patrick W. Penzias Dirks" , FreeBSD-FS@FreeBSD.ORG, FreeBSD-Arch@FreeBSD.ORG Subject: Re: Support for pivot_root-like system call? In-Reply-To: <3B225989.6E2110@mindspring.com> Date: Sat, 09 Jun 2001 12:36:30 -0700 From: Peter Wemm Message-Id: <20010609193630.E5EE9380C@overcee.netplex.com.au> Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org Terry Lambert wrote: > Peter Wemm wrote: > > Terry, the 'cache coherency' bugs have been fixed in -current for ~8 > > months now (September 2000). The infrastructure changes for this are > > subject to a call-for-review right now for a merge to 4.x. > > Peter, the 'cache coherency' bugs have only been fixed for > the trivial case where the pages at the top are identical > to the pages at the bottom of a vnode stack. Which is exactly what we're talking about - the trivial one-to-one mapping. See the example that you previously posted, but so thoughtfully removed: > > It doesn't work in FreeBSD proper because of cache coherency > > bugs that have been around since 1995, but: > > > > mount -t nullfs / /put_old # or wherever > > mount -t / > > > > Would do what you want, I think. There are no cache coherency bugs in this situation, which is all we were talking about to start with. You were the one that went off on a tangent on one-to-many mappings, but that is not related to the question at hand. (pivot_root(), remmeber...) Yes, you are absolutely correct about getpages/putpages etc being the real fix that enables all the good stuff, but that wasn't the issue at hand. Cheers, -Peter -- Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message