Date: Fri, 19 Sep 2008 11:55:05 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-stable@FreeBSD.ORG, talon@lpthe.jussieu.fr, jhb@FreeBSD.ORG Subject: Re: floppy disk controller broken Message-ID: <200809190955.m8J9t5mE092126@lurza.secnetix.de> In-Reply-To: <20080918183250.GA48347@lpthe.jussieu.fr>
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Michel Talon wrote: > Oliver Fromme wrote: > > Michel Talon wrote: > > > Moreover, trying to write to the floppy: > > > niobe# dd if=/dev/zero of=/dev/fd0 conv=noerror > > > dd: /dev/fd0: Input/output error > > > 5+0 records in > > > 4+0 records out > > > 2048 bytes transferred in 4.054404 secs (505 bytes/sec) > > > > > > I don't expect such result. Traditionnally writing works, while reading > > > may fail. > > > > Maybe I misunderstand what you're saying, but ... > > When I try to write to a floppy that has *not* been > > successfully formatted, I very much expect to get > > Input/output error. Anything else would be a bug. > > The floppy has certainly be formatted, in the past. Perhaps i > remember badly, i have not used floppies since years, but > in this case the behavior with Windows, Linux and ancient FreeBSD > was that you could write to the floppy, but could encounter errors > while reading. Since you mentioned "ancient" FreeBSD, I assume that was using buffered block devices, when FreeBSD still supported them? Nowadays /dev/fd0 is a character device which is unbuffered, i.e. your dd(1) command goes straight to the disk, and if the drive reports an error (typically sync mark not found if the floppy is unformatted), it goes back up to dd(1) immediately and you get Input/output error. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "We will perhaps eventually be writing only small modules which are identi- fied by name as they are used to build larger ones, so that devices like indentation, rather than delimiters, might become feasible for expressing local structure in the source language." -- Donald E. Knuth, 1974
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