From owner-freebsd-hackers Wed Dec 8 11: 3:43 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 8E8741583B for ; Wed, 8 Dec 1999 11:03:39 -0800 (PST) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id LAA40643; Wed, 8 Dec 1999 11:03:16 -0800 (PST) (envelope-from dillon) Date: Wed, 8 Dec 1999 11:03:16 -0800 (PST) From: Matthew Dillon Message-Id: <199912081903.LAA40643@apollo.backplane.com> To: Ben Rosengart Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Getting a new MAP_ flag into mmap() prior to 4.x freeze References: Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :I assume that this flag would require write permission to the file, to :prevent bad security implications? : :-- : Ben Rosengart You can set the flag without write permission but it will not do anything in that case. The only way to get a page marked such that the syncer doesn't sync it is if you mmap() an area of memory and then take write-faults on pages within that area, which requires write permission to succeed. Only pages dirtied through a mmap marked to not sync will not sync. Things like file meta-data always sync, though if the only data written to a file is through such an mmap() the filesystem will not have much to do there. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message