Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!howland.erols.net!surfnet.nl!newshost.vu.nl!star.cs.vu.nl!not-for-mail From: kjb=730999@cs.vu.nl (Kees J Bot) Newsgroups: comp.unix.bsd.misc,comp.os.linux.misc Subject: Re: Linux vs BSD Date: Tue, 8 Apr 1997 12:42:53 +0200 Organization: One Minix-vmd system, it works! Lines: 32 Message-ID: <df7di5.voe.ln@mega.am.cs.vu.nl> References: <32DFFEAB.7704@usa.net> <slrn5fejrn.353.bet@onyx.interactive.net> <E8A0C3.27o.0.staffin.dcs.ed.ac.uk@dcs.ed.ac.uk> NNTP-Posting-Host: mega.am.cs.vu.nl Xref: euryale.cc.adfa.oz.au comp.unix.bsd.misc:2954 comp.os.linux.misc:168699 In article <E8A0C3.27o.0.staffin.dcs.ed.ac.uk@dcs.ed.ac.uk>, Scott Telford <st@epcc.ed.ac.uk> wrote: >In article <5gjsc9$2cm@innocence.interface-business.de>, J Wunsch >(j@ida.interface-business.de) wrote: > >> This might be because Linux doesn't have the concept of a `raw device' >> at all. I always wondered why they diminished this idea, and the > >I suspect it's mainly because Minix didn't have raw devices either. Only because they weren't present in /dev/. You could create them with mknod and they would work, although a bit limited because the disk drivers only expected I/O in kilobyte units, the file systems block size. Today's Minix can now do raw I/O with any multiple of the disks true block size (usually 512 bytes). There are still no raw devices in /dev/, because it seems better to let the few utilities that might need them create the devices on the fly. (The floppy formatting command does this.) This keeps the already overpopulated /dev/ clean. >The legacy of Linux's origins can still be found if you look closely... Linus may have missed the concept of raw devices because Minix didn't make a point of mentioning the idea, neither in /dev/ nor in the code. The Minix file system code simply looks at a block device as something that needs buffering and that can act as a file system. Under Minix-vmd if we want to now how much overhead the file system cache has we simply make a block device of /dev/zero, measure how fast we can read from it and weep. -- Kees J. Bot, Systems Programmer, Vrije Universiteit Amsterdam Minix: http://www.cs.vu.nl/ftp/minix/ ftp://ftp.cs.vu.nl/pub/minix/ Minix-vmd: http://Minix-vmd.cs.vu.nl/ ftp://Minix-vmd.cs.vu.nl/