Date: Sat, 09 Jun 2001 12:36:30 -0700 From: Peter Wemm <peter@wemm.org> To: tlambert2@mindspring.com Cc: "Patrick W. Penzias Dirks" <pwd@apple.com>, FreeBSD-FS@FreeBSD.ORG, FreeBSD-Arch@FreeBSD.ORG Subject: Re: Support for pivot_root-like system call? Message-ID: <20010609193630.E5EE9380C@overcee.netplex.com.au> In-Reply-To: <3B225989.6E2110@mindspring.com>
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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 <whatever> / > > > > 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
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