Date: Mon, 29 Jan 2001 20:40:01 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Brian Somers <brian@Awfulhak.org> Cc: Peter Wemm <peter@netplex.com.au>, freebsd-arch@FreeBSD.ORG Subject: Re: Cloned open support Message-ID: <23397.980797201@critter> In-Reply-To: Your message of "Mon, 29 Jan 2001 18:38:24 GMT." <200101291838.f0TIcO203434@hak.lan.Awfulhak.org>
next in thread | previous in thread | raw e-mail | index | archive | help
In message <200101291838.f0TIcO203434@hak.lan.Awfulhak.org>, Brian Somers writes: >> Brian Somers wrote: >> > Hi, >> > >> > I'm considering having a crack at adding support for cloned opens. >> > Before I start, I guess I've got two questions: >> > >> > 1. Is anybody else doing this. >> > >> > 2. Given that I'll need to change the d_open prototype (and >> > thus cdevsw), I'm going to affect every device driver in the >> > tree - although only changing the first arg to a (dev_t) >> > pointer, making things pretty easy to change and not too >> > unexpected for anyone that's written sysv drivers. >> >> Not necessary. dev_t *is* a pointer. Add a flag to the device flags to > >Ach, I was thinking userland-dev_t aka udev_t :-/ Yes, the >prototypes don't need to change :-D It would have to change, it would have to be pointer to pointer to do it the way you propose. >I *guess* it's cleaner to create the new vnode so that the namei >caching side of things can do it's job on the clone device. That was my conclusion as well :-) In addition it allows cloning in some cases which would otherwise not be possible. One I know various people have been seen drooling over is media determined disk names. The driver and label/slice code could read various identifiers off the disk and allow people to do things like: mount /dev/disk/serial/234723842 /mnt -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?23397.980797201>