Messages in this thread |  | | Date | Mon, 21 May 2001 13:04:05 -0500 (CDT) | From | Oliver Xymoron <> | Subject | Re: Why side-effects on open(2) are evil. (was Re: [RFD w/info-PATCH]device arguments from lookup) |
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On Mon, 21 May 2001, David Lang wrote:
> what makes you think it's safe to say there's only one floppy drive?
Read as: it doesn't make sense to have per-fd state on a single floppy device given that there's only one actual hardware instance associated with it and multiple openers don't make sense. Opening a floppy at different densities with magic filenames was an example Linus used earlier in the thread. Surely there can be more than one drive and more than one serial port.
> On Mon, 21 May 2001, Oliver Xymoron wrote: > > > On Sat, 19 May 2001, Alexander Viro wrote: > > > > > Let's distinguish between per-fd effects (that's what name in > > > open(name, flags) is for - you are asking for descriptor and telling > > > what behaviour do you want for IO on it) and system-wide side effects. > > > > > > IMO encoding the former into name is perfectly fine, and no write on > > > another file can be sanely used for that purpose. For the latter, though, > > > we need to write commands into files and here your miscdevices (or procfs > > > files, or /dev/foo/ctl - whatever) is needed. > > > > I'm a little skeptical about the necessity of these per-fd effects in the > > first place - after all, Plan 9 does without them. There's only one > > floppy drive, yes? No concurrent users of serial ports? The counter that > > comes to mind is sound devices supporting multiple opens, but I think > > esound and friends are a better solution to that problem.
-- "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
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