From: torvalds@transmeta.com (Linus Torvalds)
To: linux-kernel@vger.kernel.org
Subject: Re: PATCH 2.5.x disable BAR when sizing
Date: Fri, 20 Dec 2002 05:57:23 +0000 (UTC) [thread overview]
Message-ID: <atubg3$699$1@penguin.transmeta.com> (raw)
In-Reply-To: 20021219213712.0518B12CB2@debian.cup.hp.com
In article <20021219213712.0518B12CB2@debian.cup.hp.com>,
Grant Grundler <grundler@cup.hp.com> wrote:
>
>In April 2002, turukawa@icc.melco.co.jp sent a 2.4.x patch to disable
>BARs while the BARs were being sized. I've "forward ported" this patch
>to 2.5.x (appended). turukawa's excellent problem description and
>original posting are here:
> https://lists.linuxia64.org/archives//linux-ia64/2002-April/003302.html
>
>David Mosberger agrees this is an "obvious fix".
It is NOT an "obvious fix".
It breaks stuff horribly. When you turn off the MEM bit on the
northbridge, there are northbridges that will stop forwarding RAM<->PCI.
>We've been using this in the ia64 2.4 code stream since about August.
And it's CRAP.
DO NOT DO THIS. It locks up some machines at bootup. Hard. Total bus
lockup if you have legacy USB enabled (or anything else that does DMA,
for that matter) at the same time as probing the northbridge with this.
Trust me. If you have some new silly ia64-specific bug, the fix is
_not_ to break real and existing hardware out there.
We've had this "obviously correct" patch floating around several times,
and it even made it into the kernel at least once. It was reverted
because it is WRONG.
Linus
next prev parent reply other threads:[~2002-12-20 5:51 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-19 21:37 PATCH 2.5.x disable BAR when sizing Grant Grundler
2002-12-20 2:54 ` Alan Cox
2002-12-20 2:27 ` David Mosberger
2002-12-20 6:05 ` Linus Torvalds
2002-12-20 19:50 ` Grant Grundler
2002-12-20 20:14 ` Linus Torvalds
2002-12-20 21:22 ` Grant Grundler
2002-12-21 18:34 ` Maciej W. Rozycki
2002-12-20 20:37 ` Richard B. Johnson
2002-12-20 21:29 ` Grant Grundler
2002-12-20 5:57 ` Linus Torvalds [this message]
2002-12-20 9:42 ` David Mosberger
2002-12-20 12:53 ` Ivan Kokshaysky
2002-12-20 17:05 ` Linus Torvalds
2002-12-20 18:26 ` David Mosberger
2002-12-20 19:28 ` Linus Torvalds
2002-12-21 22:06 ` Eric W. Biederman
2002-12-21 22:44 ` Linus Torvalds
2002-12-22 7:15 ` Paul Mackerras
2002-12-22 15:03 ` Benjamin Herrenschmidt
2002-12-22 19:21 ` Ivan Kokshaysky
2002-12-23 0:29 ` Paul Mackerras
2002-12-23 15:26 ` Ivan Kokshaysky
2003-01-05 12:37 ` [patch 2.5] PCI: allow alternative methods for probing the BARs Ivan Kokshaysky
2003-01-06 0:29 ` Anton Blanchard
2003-01-06 4:14 ` Linus Torvalds
2003-01-06 5:22 ` Eric W. Biederman
2003-01-06 10:31 ` Benjamin Herrenschmidt
2003-01-06 11:32 ` Andrew Walrond
2003-01-06 22:01 ` Grant Grundler
2003-01-06 19:45 ` Grant Grundler
2003-01-07 17:05 ` Ivan Kokshaysky
2003-01-07 17:46 ` Linus Torvalds
2003-01-07 20:17 ` Grant Grundler
2003-01-08 14:47 ` Ivan Kokshaysky
2003-01-08 22:34 ` Grant Grundler
2003-01-06 15:33 ` Ivan Kokshaysky
2003-01-06 21:52 ` Grant Grundler
2003-01-06 23:19 ` Linus Torvalds
2003-01-07 0:13 ` Grant Grundler
2003-01-07 12:33 ` Alan Cox
2003-01-07 17:27 ` Ivan Kokshaysky
2003-01-07 18:46 ` Alan Cox
2003-01-07 17:44 ` Linus Torvalds
2003-01-08 16:55 ` Ivan Kokshaysky
2003-01-09 17:46 ` [patch 2.5] 2-pass PCI probing, generic part Ivan Kokshaysky
2003-01-09 17:52 ` Benjamin Herrenschmidt
2003-01-09 22:09 ` Ivan Kokshaysky
2003-01-09 22:16 ` Linus Torvalds
2003-01-09 22:26 ` Benjamin Herrenschmidt
2003-01-10 3:49 ` Alan Cox
2003-01-09 23:19 ` Ivan Kokshaysky
2003-01-09 23:35 ` Linus Torvalds
2003-01-10 1:09 ` Grant Grundler
2003-01-10 7:56 ` Eric W. Biederman
2003-01-10 19:00 ` Grant Grundler
2003-01-10 21:42 ` Ivan Kokshaysky
2003-01-10 23:07 ` Grant Grundler
2003-01-11 19:39 ` Scott Murray
2003-01-12 7:19 ` Greg KH
2003-01-13 6:28 ` Scott Murray
2003-01-10 13:35 ` Ivan Kokshaysky
2003-01-14 16:39 ` Ivan Kokshaysky
2003-01-09 18:36 ` David Mosberger
2003-01-09 19:52 ` Grant Grundler
2003-01-09 22:40 ` Ivan Kokshaysky
2003-01-09 17:48 ` [patch 2.5] 2-pass PCI probing, hotplug changes Ivan Kokshaysky
2003-01-09 17:51 ` [patch 2.5] 2-pass PCI probing, i386 USB quirk Ivan Kokshaysky
2003-01-07 17:12 ` [patch 2.5] PCI: allow alternative methods for probing the BARs Ivan Kokshaysky
2003-01-07 17:06 ` Ivan Kokshaysky
2002-12-22 19:51 ` PATCH 2.5.x disable BAR when sizing Linus Torvalds
2002-12-22 19:57 ` Eric W. Biederman
2002-12-22 10:38 ` Eric W. Biederman
2002-12-22 18:39 ` Ivan Kokshaysky
2002-12-22 19:47 ` Eric W. Biederman
2002-12-22 21:05 ` Ivan Kokshaysky
2002-12-20 18:50 ` Ivan Kokshaysky
2002-12-20 19:11 ` Linus Torvalds
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