linux-kernel - Re: bug in kernel 2.6.21-rc1-git1: conventional floppy drive cannot be mounted without hanging up the whole system

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Date:	Tue, 27 Feb 2007 21:42:16 -0500
From:	Bill Davidsen <davidsen@....com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Rene Herman <rene.herman@...il.com>,
	Oleg Nesterov <oleg@...sign.ru>,
	Stephane Eranian <eranian@....hp.com>,
	linux-kernel@...r.kernel.org
Subject: Re: bug in kernel 2.6.21-rc1-git1: conventional floppy drive cannot
   be mounted without hanging up the whole system

Linus Torvalds wrote:
> 
> On Mon, 26 Feb 2007, Rene Herman wrote:
>> Other than these two, ECP parallel ports are the other remaining users.
>> Now, even though on a machine that still has a parallel port it might usually
>> indeed be set to ECP in its BIOS; having anything attached to the port also
>> use it as such seems quite seldom.
> 
> Well, if it's some kind of cache coherency problem (the same way much more 
> modern CPU's have cache coherency issues with DMA during C3 sleep), then 
> it's entirely possible that the normal ECP parallel port behaviour would 
> never show it, since most people tend to use it for output only (yeah, I 
> realize you can use it bidirectionally, but at least on old hardware it 
> tends to be "talk AT printer" rather than "talk WITH printer".

The bidirectional use is/was PL/IP, aka "laplink" connections. Yes, I 
still have a machine I installed that way, and it will run 2.2.19 
forever before I try it again. ;-)
> 
> I frankly forget what hardware platforms had problems with the DMA thing, 
> and what the exact behaviour even was (I think there was some possibility 
> of corrupt data on the floppy). We also used to have the "nohlt" flag to 
> turn off hlt entirely, and that was due to some other legacy issues, iirc.
> 
> I seriously doubt we will ever see anybody who has this problem ever 
> again, but on the other hand, I also seriously doubt that most modern 
> machines even *have* a floppy drive any more, so I'd rather not even 
> change it. It's just not worth even a miniscule risk..

Thank you.
> 
> 		Linus


-- 
Bill Davidsen <davidsen@....com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot
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