Date: Fri, 08 Jun 2001 08:30:11 -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: <20010608153011.D7AF1380C@overcee.netplex.com.au> In-Reply-To: <3B2096AB.309B2D14@mindspring.com>
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Terry Lambert wrote: > "Patrick W. Penzias Dirks" wrote: > > > > Hi, > > > > I'm the filesystems tech lead in Apple's Mac OS X Core OS group. > > Prompted by the needs of, among others, virus protection software > > developers who want to be able to mount "on" the root directory to > > intercept ALL filesystem calls in the system, I'm contemplating > > implementation of a new system call in Mac OS X to do something like > > Linux's pivot_root system call: > > > > int pivot_root(const char *new_root, const char *put_old); > > > > (which basically installs "new_root" as the new "/" [root_vnode] in > > the system and transfers the current root directory to the pathname > > specified my "put_old") > > 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. 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. 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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