From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from 8bytes.org ([85.214.48.195] helo=mail.8bytes.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1URgUg-0006Kd-GK for kexec@lists.infradead.org; Mon, 15 Apr 2013 10:18:40 +0000 Received: from localhost (localhost [127.0.0.1]) by mail.8bytes.org (Postfix) with SMTP id 3351D12B07F for ; Mon, 15 Apr 2013 12:18:30 +0200 (CEST) Date: Mon, 15 Apr 2013 12:18:29 +0200 From: Joerg Roedel Subject: Re: [PATCH] intel-iommu: Synchronize gcmd value with global command register Message-ID: <20130415101829.GP6858@8bytes.org> References: <20130326144629.GB2727@8bytes.org> <51527D74.9080209@jp.fujitsu.com> <20130327103122.GK30540@8bytes.org> <51591EEE.60401@jp.fujitsu.com> <20130402140546.GA15687@8bytes.org> <515BD638.8070307@jp.fujitsu.com> <1364977479.28127.15.camel@i7.infradead.org> <20130405110616.GB6858@8bytes.org> <5164EEE6.8000707@jp.fujitsu.com> <516BC19D.4090303@jp.fujitsu.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <516BC19D.4090303@jp.fujitsu.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Takao Indoh Cc: kexec@lists.infradead.org, iommu@lists.linux-foundation.org, dwmw2@infradead.org, linux-kernel@vger.kernel.org, tindoh@gmail.com On Mon, Apr 15, 2013 at 06:00:13PM +0900, Takao Indoh wrote: > On DMAR initialization during kdump boot, do you guys agree to change > order like this? > > Current order: > (1) Disable translation > (2) PCI initialization > (3) Make pgtable and enable translation. > > Order I'm proposing: > (1) PCI initialization > (2) Disable translation > (3) Make pgtable and enable translation. I think this should work. In fact, translation only needs to be disabled while the IOMMU hardware is reprogrammed to the new data structures the kdump kernel set up. > As Joerg said, if we need to consider the case that kdump kernel is > compiled without dma-remapping(CONFIG_INTEL_IOMMU is off?), I can update > my patch to handle such a case properly by adding ifdef > CONFIG_INTEL_IOMMU. Thinking about it, this case is a bit more special. If the kdump kernel has no IOMMU driver at all there is also no code to disable it. So unless we want to force the kdump kernel to have the driver when the first kernel had it, I think we also want some quirk (depending on !CONFIG_INTEL_IOMMU) that disables translation at boot. I know, its complicated :) Joerg _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec