Date: Sat, 14 Feb 1998 02:36:35 -0200 (EDT) From: Joao Carlos Mendes Luis <jonny@coppe.ufrj.br> To: julian@whistle.com (Julian Elischer) Cc: mike@smith.net.au, phk@critter.freebsd.dk, committers@FreeBSD.ORG Subject: Re: devfs persistance Message-ID: <199802140436.CAA01747@gaia.coppe.ufrj.br> In-Reply-To: <Pine.BSF.3.95.980213171931.23295X-100000@current1.whistle.com> from Julian Elischer at "Feb 13, 98 05:26:36 pm"
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Some questions about DEVFS. (Shouldn't this go to freebsd-hackers ?) 1) What will be the impact on hand-created devices ? Will still be possible to simply mknod some file on some dir and use it ? I don't like the ideia of having to use DEVFS on chrooted environments. In such environments not all devices should be seen, and the permissions could be even different from the defaults. 2) What's the practical meaning of "turning DEVFS default" ? 3) Will DEVFS in any sense make major numbers random ? if so, my #1 question is already answered. Not to hardcode device number is good, but letting the kernel choose them on the fly is not good. I like, for example, the Solaris' /etc/name_to_major approach. Persistence is desirable IMHO. Again, Solaris' /etc/minor_perm is something I've got used to after some disliking at first view. Using unionfs syntax for persistence is not easy to deal or keep organized. I prefer editing a single file (although not /etc/rc.local :) ). Please, please, please, forget the sysctl idea for this. And a daemon is not good, also. But in Solaris, /devices is not a new FS, it's just a standard UFS with devices that are created automagically by the kernel if booted with the -r flag. They don't need a daemon, but need an add_drv program (eek). I still don't have an ideia of how to get this into the DEVFS approach of keeping device file information in kernel memory. Being said the above, I think I like Mike Smith's approach of /dev/devperm. But there's no need of a backing store. Just put a "cat /etc/minor_perm > /dev/devperms" right after mounting /dev. If you need any change, just edit the file and cat it again. The file could be read to get the current configuration, but a change into the mounted system would not reflect into it. Or maybe the could be another device that would read the current config. Maybe a sysctl is needed for the name_to_major approach, since it needs to be loaded before mounting. Jonny -- Joao Carlos Mendes Luis jonny@gta.ufrj.br +55 21 290-4698 jonny@coppe.ufrj.br Universidade Federal do Rio de Janeiro UFRJ/COPPE/CISI PGP fingerprint: 29 C0 50 B9 B6 3E 58 F2 83 5F E3 26 BF 0F EA 67 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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