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Date:      Wed, 19 Jun 2002 16:20:09 -0700 (PDT)
From:      "Jin Guojun[DSD]" <j_guojun@lbl.gov>
To:        freebsd-bugs@FreeBSD.org
Subject:   Re: kern/39449: wierd ata status
Message-ID:  <200206192320.g5JNK9B25976@freefall.freebsd.org>

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The following reply was made to PR kern/39449; it has been noted by GNATS.

From: "Jin Guojun[DSD]" <j_guojun@lbl.gov>
To: cjclark@alum.mit.edu
Cc: bug-followup@freebsd.org
Subject: Re: kern/39449: wierd ata status
Date: Wed, 19 Jun 2002 16:20:36 -0700

 "Crist J. Clark" wrote:
 > 
 > On Wed, Jun 19, 2002 at 01:45:02PM -0700, Jin Guojun[DSD] wrote:
 > > "Crist J. Clark" wrote:
 > > >
 > > > On Wed, Jun 19, 2002 at 01:03:17AM -0700, Jin Guojun[DSD] wrote:
 > > > [snip]
 > > >
 > > > > I am not able to access these machines till Friday.
 > > > > Unless you think the regular dmesg will help, I will send you full message
 > > > > with "boot -v" on Friday.
 > > >
 > > > The regular boot messages may help.
 > >
 > > Below is dmesg from 4.6 machine, and a set of -v message from a 4.5
 > > machine with the identical hardware we used before.
 > > The message of 4.6 and the first message of 4.5 are from customer built
 > > kernel, which has ata1 disabled in kernel config file. The 4.5 has no ata1
 > > configured, but 4.6 has ata1 configured.
 > >
 > > The rest of messages of 4.5 is from GENERIC kernel (original from
 > > the installation) with following conditions:
 > >
 > > #2, just -v option. We see both ata0 and ata1 configured.
 > >
 > > #3, the secondary IDE is disbaled in BIOS, and ata1 is not configured.
 > > #4, the disk is removed from the secondary IDE bus, and ata1 is not
 > >  configured.
 > >
 > > So, in 4.5, we have muliplte ways to disble ata1, but in 4.6 we have none.
 > 
 > OK, I think the dmesg(8) shows what I think is going on. You never
 > "disabled" ata1 in 4.5-RELEASE by doing anything to the kernel
 > configuration. In 4.5-RELEASE, if there was no hardware attached to
 > ata1, the probe turns up nothing,
 >
 > > #3 ----------- GENERIC kernel with second IDE disabled in BIOS ------
 > > Copyright (c) 1992-2002 The FreeBSD Project.
 > > Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
 > >         The Regents of the University of California. All rights reserved.
 > > FreeBSD 4.5-RELEASE #0: Mon Jan 28 14:31:56 GMT 2002
 > >     murray@builder.freebsdmall.com:/usr/src/sys/compile/GENERIC
 > [snip]
 > > ata1: iobase=0x0170 altiobase=0x0376 bmaddr=0xd808
 > > ata1: mask=00 status0=ff status1=ff
 > > ata1: probe allocation failed
 > 
 > But it is still probed. You are not disabling it in the kernel
 > configuration, it is disabling itself when no devices are found.
 > 
 > In 4.6-RELEASE, we have support for removable ATA devices. Even if
 > ata1 doesn't have anything when probed at boot, we want to attach the
 > device in order to have it available for swapping devices.
 > 
 > So, to summarize, you have never had the ability to disable PCI ATA
 > devices in the kernel configuration. However, in 4.5-RELEASE, ata(4)
 > devices with nothing attached to them were not allocated resources. In
 > 4.6-RELEASE, ata(4) devices are allocated in order to support
 > removable devices (which is totally wicked-cool BTW, see
 > atacontrol(8)).
 
 It is good to support removable devices. But remember that in 4.5 we have
 two ways to disable ata1:
 (1) no device attached
 or 
 (2) disbale the secondary IDE in BIOS.
 
 If 4.6 or later could distinguish these two cases, it will make this
 feature more useful. If users want to use removeable devices, enable
 the IDE in BIOS, but leave devices either attached or unattached; 
 if users do not want to use IDE at all, disable IDE in BIOS.
 
 I do not see why this cannot be implemented as in 4.5.
 
 > Or at least, that's how I am reading things. Soren would be able to
 > verify my educated guesses here and provide the details.
 > --
 > Crist J. Clark                     |     cjclark@alum.mit.edu
 >                                    |     cjclark@jhu.edu
 > http://people.freebsd.org/~cjc/    |     cjc@freebsd.org
 
 -- 
 ------------ Jin Guojun ----------- v --- j_guojun@lbl.gov ---
 Distributed Systems Department		http://www.itg.lbl.gov/~jin
 M/S 50B-2239				Ph#:(510) 486-7531 Fax: 486-6363
 Lawrence Berkeley National Laboratory,	Berkeley, CA 94720

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