From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] intel-iommu: Synchronize gcmd value with global command register Date: Tue, 2 Apr 2013 16:05:47 +0200 Message-ID: <20130402140546.GA15687@8bytes.org> References: <1363829556-2128-1-git-send-email-indou.takao@jp.fujitsu.com> <20130326144629.GB2727@8bytes.org> <51527D74.9080209@jp.fujitsu.com> <20130327103122.GK30540@8bytes.org> <51591EEE.60401@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <51591EEE.60401-+CUm20s59erQFUHtdCDX3A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Takao Indoh Cc: kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Mon, Apr 01, 2013 at 02:45:18PM +0900, Takao Indoh wrote: > > enable_IR > intel_enable_irq_remapping > iommu_disable_irq_remapping <== IRES/QIES/TES disabled here > dmar_disable_qi <== do nothing > dmar_enable_qi <== QIES enabled > intel_setup_irq_remapping <== IRES enabled But what we want to do here in the kdumo case is to disable translation too, right? Because the former kernel might have translation and irq-remapping enabled and the kdump kernel might be compiled without support for dma-remapping. So if we don't disable translation here too the kdump kernel is unable to do DMA. I agree that disabling translation should be a bit more explicit instead of the current code. Joerg