From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from szxga01-in.huawei.com ([119.145.14.64]:12743 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753322Ab2FTIeR (ORCPT ); Wed, 20 Jun 2012 04:34:17 -0400 Message-ID: <4FE18A9B.9040501@huawei.com> Date: Wed, 20 Jun 2012 16:32:27 +0800 From: Jiang Liu MIME-Version: 1.0 To: Yinghai Lu CC: Bjorn Helgaas , Taku Izumi , Kenji Kaneshige , Don Dutile , Yijing Wang , Keping Chen , , Jiang Liu Subject: Re: [PATCH v8 06/12] PCI/ACPI: provide MCFG address for PCI host bridges References: <1340111732-6276-1-git-send-email-jiang.liu@huawei.com> <1340111732-6276-7-git-send-email-jiang.liu@huawei.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Sender: linux-pci-owner@vger.kernel.org List-ID: Hi Yinghai, > thought you were agreeing to go through choice 2 without caching MCFG anymore. > > Can you just drop that caching MCFG and only handle _CBA here? > > Thanks > > Yinghai Yes, I'm going to adopt solution two as you suggested. On the other hand, the MMCFG caching is kept due to following considerations: 1) To emit a warning message if MMCFG entries in MCFG table only partially covers buses under a PCI host bridge. Taku reported that he has a system which exhibits such a behavior. 2) To cross-check that MMCFG addresses returned by MCFG table and _CBA method are consistent if both are available (though that violates the PCI FW/ACPI specifications). 3) In future, we may try to remove MMCFG entry constructed from MCFG table when hot-removing a PCI host bridge. We have some systems which assign a distinguish segment ID for each host bridge. In such a case, it may be reasonable to remove the MMCFG entry when removing a host bridge. 4) The MCFG cache should be small under normal cases. If you feel it's unnecessary to keep the cache, I will remove it and send out a updated version soon. Thanks! Gerry