From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:11315 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759170Ab2IKOpf (ORCPT ); Tue, 11 Sep 2012 10:45:35 -0400 Date: Tue, 11 Sep 2012 10:43:23 -0400 From: Vivek Goyal To: Takao Indoh Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, bhelgaas@google.com, hbabu@us.ibm.com, ishii.hironobu@jp.fujitsu.com, martin.wilck@ts.fujitsu.com Subject: Re: [RFC][PATCH] Reset PCIe devices to address DMA problem on kdump with iommu Message-ID: <20120911144323.GF12039@redhat.com> References: <501BB4EF.7080909@jp.fujitsu.com> <20120803114643.GA28330@redhat.com> <501F4877.5050605@jp.fujitsu.com> <20120806203902.GH25559@redhat.com> <50473306.1070803@jp.fujitsu.com> <20120910143604.GB639@redhat.com> <504F1343.7030607@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <504F1343.7030607@jp.fujitsu.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, Sep 11, 2012 at 07:32:35PM +0900, Takao Indoh wrote: [..] > I'll post new patch which clears bus master bit and resets devices in > second kernel. > > As to the boot parameter to enable this function, you suggested using > reset_devices. I found that on a certain platform resetting devices > caused PCIe error due to a hardware bug. Therefore I think we need > new parameter apart from reset_devices to disable this function on > such a machine. Can you explain a bit more how the error happens. I still don't think that because of a bug in a platform somewhere we should be introducing a separate command line parameter and not reuse the exisiting one. Also you have not explained what's the bug and how a new parameter will avoid the bug. Thanks Vivek