Date: Wed, 22 Jan 2003 07:18:30 -0500 (EST) From: Robert Watson <rwatson@FreeBSD.ORG> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Peter Wemm <peter@wemm.org>, phk@FreeBSD.ORG, "Alan L. Cox" <alc@imimic.com>, arch@FreeBSD.ORG Subject: Re: getsysfd() patch #1 (Re: Virtual memory question) Message-ID: <Pine.NEB.3.96L.1030122065201.47551B-100000@fledge.watson.org> In-Reply-To: <200301220424.h0M4OdZn000391@apollo.backplane.com>
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On Tue, 21 Jan 2003, Matthew Dillon wrote: > Hmm. Well, the opengroup manual page for fattach() basically says > that you fattach(filedes, path) to an existing file and operations on > the file are then operations on filedes, but the manual page is > specifically STREAM oriented. We could use it for other types of > file descriptors but I'm somewhat worried about how error conditions > would be detected... for a memory descriptor how do you know you are > mmap()ing the memory descriptor rather then the file? Yeah, I have to admit I'm not thrilled by these prospects -- there are lots of places in the kernel where we directly operate on the vnode w/o a struct file, or the supporting device, etc. Implementing consistent semantics would be daunting at best. One of the nice things about the current patch + rename to memfd system call was the pure simplicity of it. It introduces one new type of object created by a simple system call, and then a single operation on it, mmap(). I recognize the benefits of explicit namespaces in IPC, of course... Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Network Associates Laboratories To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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