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Date:      Mon, 20 Sep 2004 08:23:56 +0200
From:      "Poul-Henning Kamp" <phk@phk.freebsd.dk>
To:        Warner Losh <imp@FreeBSD.org>
Cc:        cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/dev/fdc fdc_isa.c 
Message-ID:  <44715.1095661436@critter.freebsd.dk>
In-Reply-To: Your message of "Mon, 20 Sep 2004 06:12:19 -0000." <200409200612.i8K6CJ12009866@repoman.freebsd.org> 

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In message <200409200612.i8K6CJ12009866@repoman.freebsd.org>, Warner Losh write
s:

>  It accesed FDSTS and FDDATA incorrectly via the second resource (which
>  wound up accessing FDOUT and the tape register at 0x3f3) and badly for
>  the CTL register (at location 0x3f4).  This is a minimal fix that just
>  'eats' the first one if it covers two locations and has an offset of
>  0.  This confusion lead the floppy driver to think there'd been a disk
>  change, which uncovered a deadlock in the floppy/geom code which lead
>  to a panic.

The "deadlock" is only there if the disk-change line goes from
active to inactive when it shouldn't.  To reset this pin it is necessary
to execute a step to the controller. 

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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