Date: Thu, 02 Aug 2001 21:59:24 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: Rik van Riel <riel@conectiva.com.br> Cc: mark tinguely <tinguely@web.cs.ndsu.nodak.edu>, culverk@wam.umd.edu, craiglei@pasia.com.cn, freebsd-hackers@FreeBSD.ORG Subject: Re: How to visit physical memory above 4G? Message-ID: <3B6A2FAC.28F2F959@mindspring.com> References: <Pine.LNX.4.33L.0108021115500.5582-100000@duckman.distro.conectiva>
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Rik van Riel wrote: > > The addressing use 64 bits for a memory pointer and the additional > > page indirection add to the overhead. The stickler is the MMU is > > still 32 bits. This means the PAE must segment the 64GB space into > > 4GB segments or 4 1GB segments. The OS must manage which pages are > > viewable to the process at this time. > > There's a better option. The application does this stuff > itself, by mapping and unmapping SHM segments. Not surprisingly, this doesn't work if your application is the kernel, and the data is mbufs, open file structures, sockets, tcpcb's, or inpcb's. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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