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Date: Fri, 12 Dec 2003 10:20:25 -0500 (EST)
From: "Richard B. Johnson" <root@chaos.analogic.com>
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To: =?iso-8859-1?q?M=E5ns_Rullg=E5rd?= <mru@kth.se>
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Subject: Re: PROBLEM: floppy motor spins when floppy module not installed
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On Fri, 12 Dec 2003, [iso-8859-1] Måns Rullgård wrote:

> "Richard B. Johnson" <root@chaos.analogic.com> writes:
>
> > On Fri, 12 Dec 2003, [iso-8859-1] Måns Rullgård wrote:
> >
> >> Dale Mellor <dale@dmellor.dabsol.co.uk> writes:
> >>
> >> > 1. Floppy motor spins when floppy module not installed.
> >>
> >> It's a known problem.  Some broken BIOSes don't turn off the motor
> >> after probing for a disk.  One solution is to change the boot priority
> >> in the BIOS settings so the hard disk is tried before floppy.  If you
> >> ever need to boot from a floppy, you can change it back.
> >
> > It is not a broken BIOS! The BIOS timer that ticks 18.206 times
> > per second has an ISR that, in addition to keeping time, turns
> > OFF the FDC motor after two seconds of inactivity. This ISR is taken
> > away by Linux. Therefore Linux must turn off that motor! It is a
> > Linux bug, not a BIOS bug. Linux took control away from the BIOS
> > during boot.
>
> OK, but why doesn't it affect all machines?
>
If you leave the FDC software in the kernel, the FDC software
sets up everything and turns off the motor. If you have the
FDC as a module, you have nothing in there to turn off the
motor until you install the module.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.22 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.