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Date:      Fri, 4 May 2012 11:18:56 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Hans Petter Selasky <hselasky@c2i.net>
Cc:        "svn-src-stable@freebsd.org" <svn-src-stable@FreeBSD.ORG>, "svn-src-all@freebsd.org" <svn-src-all@FreeBSD.ORG>, "src-committers@freebsd.org" <src-committers@FreeBSD.ORG>, "svn-src-stable-9@freebsd.org" <svn-src-stable-9@FreeBSD.ORG>, John Baldwin <jhb@FreeBSD.ORG>
Subject:   Re: svn commit: r235007 - stable/9/sys/dev/pci
Message-ID:  <FEA446E9-A651-40F7-BFDD-1A2D41360EB8@bsdimp.com>
In-Reply-To: <201205041826.19435.hselasky@c2i.net>
References:  <201205041538.q44FclqK010547@svn.freebsd.org> <201205041214.16342.jhb@freebsd.org> <201205041826.19435.hselasky@c2i.net>

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On May 4, 2012, at 10:26 AM, Hans Petter Selasky wrote:

> On Friday 04 May 2012 18:14:16 John Baldwin wrote:
>> On Friday, May 04, 2012 11:38:47 am Hans Petter Selasky wrote:
>>> Author: hselasky
>>> Date: Fri May  4 15:38:47 2012
>>> New Revision: 235007
>>> URL: http://svn.freebsd.org/changeset/base/235007
>>>=20
>>> Log:
>>>  MFC r233662, r233677 and r233678:
>>>=20
>>>  Writing zero to BAR actually does not disable it and
>>>  it is even harmful as hselasky found out.  Historically,
>>>  this code was originated from (OLDCARD) CardBus driver and later =
leaked
>>>  into PCI driver when CardBus was newbus'ified and refactored with =
PCI
>>>  driver. However, it is not really necessary even for CardBus.
>>=20
>> FYI, I've got one bug report on HEAD where these changes broke a =
machine's
>> ATA controller.
>=20
> Have you considered adding code to disable the I/O or memory range =
instead of=20
> writing 0 to the bar in this case?

I tried that once upon a time, but was problematical with some bridges =
that had BARs at non-standard locations that needed the I/O or MEM bit =
set in order to work...

Warner




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