From: becker@super.org (Donald J. Becker) Subject: Re: 'floppy: unexpected interrupt' on SLS .99p8 Date: Mon, 19 Apr 1993 19:06:37 GMT
In article <1qru0nINNkrr@senator-bedfellow.MIT.EDU> pan@athena.mit.edu (Howard Wei-Hao Pan) writes:
> ke@doc.ic.ac.uk (K Evangelinos) wrote:
>>I recently FTP'ed and tried to use the SLS version of Linux. I booted the A1
>>disk, and fed A2 later. Once booted, I tried to see the /user/README file.
>>While my more waits for keys, I get messages saying 'floppy: unexpected
>>interrupt' while the floppy drive doesn't (apparently) do anything. I thought
>>switching the turbo off might stop it, but on the contrary, things seem to
>>get worse.
>
>Hmmn...that's really weird. I was installing Linux last night on my laptop, and
>got this message too. (That was with version 0.99p6 I believe). However, the
>"floppy: unexpected interrupt" message only appeared when I was not connected
>to an AC adapter--so I presumed it was because the system was trying to
>conserver power by sending power down signals to the floppy drive or something
>or another. But since you were getting it on your desktop, I'm beginning to
>wonder why that is.
It is normal for laptops to report "unexpected interrupt" after they
have powered down the floppy disk interface due to inactivity. I've
gotten around this by the equivalent of "cp /dev/fd0 /dev/fd0 ... >
/dev/null" during an install, but there is probably a better way.
It's far more common to encounter this problem with a hard-disk, since
that's something that in daily use. Most modern IDE disks (even those
on full-sized-systems) implement semi-standardized commands for
timer-based idle and shutdown modes. Those commands are in the
0xE0-0xE6 range for those that have a IDE driver reference manual handy.
I hate to be so trendy, and shutting down a modern hard disk saves
relatively little power*, but Linux could be the first "Green PC" OS!
[[Ed. The "Green PC" campaign, snort, it look like just another meaningless
advertising ploy.]]
Power control on devices is a Good Thing, and many of the laptop power
control features are likely to migrate to full-sized systems. Linux
has an significant advantage over MS-DOS: we know when a device is in
use. Device driver writers should consider the possibility and effect
of a device power-down. For instance, laptop serial ports may be
turned off, but typically need to have the register contents restored
later. Some ethercards can turn off their transceiver power, but
should have a turn-on delay before transmitting. And some processors
have power management modes.
* The most useful attribute: shutting off the disk can make a laptop
completely silent.
-- Donald Becker becker@super.org Supercomputing Research Center 17100 Science Drive, Bowie MD 20715 301-805-7482