Date: Fri, 24 Aug 2001 22:59:13 -0700 From: Peter Wemm <peter@wemm.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: Julian Elischer <julian@elischer.org>, Alfred Perlstein <bright@mu.org>, David Greenman <dg@root.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: Possible race in i386/i386/pmap.c:pmap_copy() Message-ID: <20010825055913.1ED783810@overcee.netplex.com.au> In-Reply-To: <200108250132.f7P1WfR03688@earth.backplane.com>
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Matt Dillon wrote: > > : > :Thinking about this a bit more.... > :doesn't each process ahve it's own PTD?, so a process could sleep and > :another could run but it would have a differnt PTD > :so they could change that PTDE with impunity > :because when teh current process runs again it get's its own > :ptd back again.. > > Hmm. Ok, I think you are right. APTDpde is what is being loaded > and that points into the user page table directory page, which is > per-process. So APTDpde should be per-process. But it is! (sort-of) APTDpde was per-process but is now per-address-space with the advent of fork and RFMEM sharing (and KSE). When we context switch, PTD goes with the process^H^H^H^Haddress space, and APTD is merely mapped by the last entry in the per-process PTD (PTD[APTDPDTI] if memory serves correctly). 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-hackers" in the body of the message
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