Date: Sat, 22 Jan 2000 13:12:17 +0800 From: Greg Lehey <grog@lemis.com> To: Brian Beattie <beattie@aracnet.com> Cc: Kelly Yancey <kbyanc@posi.net>, fs@FreeBSD.ORG, Poul-Henning Kamp <phk@FreeBSD.ORG> Subject: Re: UDF, userfs Message-ID: <20000122131216.B391@mojave.worldwide.lemis.com> In-Reply-To: <Pine.LNX.4.10.10001211409120.28236-100000@shell1.aracnet.com>; from beattie@aracnet.com on Fri, Jan 21, 2000 at 02:21:58PM -0800 References: <Pine.BSF.4.05.10001211604320.71794-100000@kronos.alcnet.com> <Pine.LNX.4.10.10001211409120.28236-100000@shell1.aracnet.com>
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On Friday, 21 January 2000 at 14:21:58 -0800, Brian Beattie wrote: > On Fri, 21 Jan 2000, Kelly Yancey wrote: > >> On Fri, 21 Jan 2000, Brian Beattie wrote: >> >>> I have been thinking about the userfs implementation. I will need some >>> way for the user process to talk the backend of the userfs kernel code. >>> The two ways I have thought of are I/O,, probably ioctl's or a new system >>> call. >>> > ... >> Perhaps you have put more thought into it, but >> the concern that immediately comes to my mind is how to get VOP function >> calls from kernel-space to user-space. Some kind of up-call mechanism >> seems in order. You had suggested a pseudo-device, presumably with the >> intent to have daemons which implement file systems to read from to >> catch VOPs and write to to return data. > > Basicaly, the user process that implements the filesystem, would issue a > calls (i assume an ioctl on a pseudo device, but I am open to > suggestions). The userfs module would pass any VOP's back to the process, > or return an empty result. One could also implement select support. > (exact details still open) Well, in fact, you just need to interface directly to a block device. Oh. We don't have any block devices any more. phk, remember the discussion we had about this? I was saying "just because nobody can think of a good use for a block device right now doesn't mean that somebody won't come". Now Brian has come. Can we somehow resurrect a block device interface from userland? I don't think we should reintroduce block devices per se, but it would nice to have an ioctl call which says "use block device semantics for this file handle". What do you think? Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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