Date: Fri, 25 Oct 2002 11:05:04 -0700 (PDT) From: Julian Elischer <julian@elischer.org> To: Mark Valentine <mark@thuvia.demon.co.uk> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, "M. Warner Losh" <imp@bsdimp.com>, freebsd-arch@freebsd.org Subject: Re: cvs commit: src/lib/libdisk Makefile chunk.c write_alpha_disk.c write_i386_disk.c write_pc98_disk.c Message-ID: <Pine.BSF.4.21.0210251041050.6512-100000@InterJet.elischer.org> In-Reply-To: <200210251735.g9PHZ1sT075954@dotar.thuvia.org>
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On Fri, 25 Oct 2002, Mark Valentine wrote: > > I'm sure we'll appreciate the progress you've made once we've seen what > it gives us. We're simply asking why we have to sacrifice a traditional > interface (and in my experience one which is more reliable) to buy into it. > > What is the cost of having both? You can't have both because the naming scheme gives a particular name to a partition because of how you get to it.. ad0a means: I openned the disk, found a disklabel and this is the first partition defined in that disklabel. We've been (except for Bruce, (often right, but not one to part with old ways)) moving towards doing this for the last 10 years.. Devfs and it's associated disk-recarving code have been postulated and prototyped singe 1993. We have made the default disk names installed the "new, reality based" ones since about 1996. If someone doesn't know what ad0s1a means yet then they haven't been paying attention. As new devices come and go in the new 'pluggable, wireless world' the old scheme of assigning for all eternity a particular set of limitted availability bits to a particular drive and part of that drive, has to give way to something else. Devfs is one possibility for this, but devfs cannot easily cope with the multiple ways that drive partitionning can be layered, without breaking away from the traditional fixed geometry<->minor-number/naming scheme. In the old scheme there is just NO WAY to describe some partitioning schemes, especially in the plug-in world where the drive may have been partitioned by some medical imaging system or a MAC or a SUN. Our hand is being forced. <dreaming> In the future I feel that the default names may eventually be over-ridden by semantically meaningfull names. e.g. You may partition a drive and give each partition a name which might be used instead of the default inherrited name.. e.g. ad0s1s2b (not a typo) may decide that it would rather be known "/dev/swap2" because the table entry has a field "swap%d" in it, or disk2 may decide that it wants to be known as "/dev/tunes". (A removable disk full of music) These things are possible with devfs. /dev/tunes-s1a would be a partition on that drive.. it's removable so when you replace it with the drive that calls itself "/dev/backups" the /dev/entries correct themselves. But that is all just potential at this stage. </dreaming> To address some of your concerns We COULD have a /dev/ad0sBa that always reflects the first BSD slice "a" partition. that would give the characteristics you have asked for.. and still abides by the naming convention.. (devfs could make a symlink or something..) but ad0a is already taken.. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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