Date: Fri, 09 Nov 2001 13:54:43 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Jason Mawdsley <jason@macadamian.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: mmap/madvise Message-ID: <3BEC50A3.73AD7834@mindspring.com> References: <200111081947.fA8JlAe03457@web.cs.ndsu.nodak.edu> <02ae01c16891$4c1f4970$2a64a8c0@macadamian.com> <3BEB0A57.3C510C49@mindspring.com> <019401c16959$4e64a8b0$2a64a8c0@macadamian.com>
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Jason Mawdsley wrote: > > > > I am creating a virtual memory manager. > > > > > > Currently I am doing a > > > mmap(...PROT_NONE, MAP_ANON ) to reserve the memory. > > > then when committing the memory I am using mprotect( ...PROT_READ | > > > PROT_WRITE ) > > > > mmap For reservation of memory; you should > > mmap the fd for /dev/zero, with MAP_ANON > > to grab pages initially. > > The man pages state that the fd must be -1 for MAP_ANON. > an open() /dev/zero will return an valid file descriptor. So how would I > mmap using /dev/zero? Mmap'ing /dev/zero gives you anopnymous pages; they can't be not private. It's pretty much the same thing. I would use /dev/zero, since it's portable. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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