From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out01.mta.xmission.com ([166.70.13.231]) by bombadil.infradead.org with esmtp (Exim 4.68 #1 (Red Hat Linux)) id 1KWgSC-0001PL-PH for kexec@lists.infradead.org; Fri, 22 Aug 2008 23:54:05 +0000 From: ebiederm@xmission.com (Eric W. Biederman) References: <1218138156.3361.386.camel@amd.troyhebe> <20080808014024.GB3911@redhat.com> <1218750773.3361.425.camel@amd.troyhebe> <20080815131359.GA10208@redhat.com> <1219081942.3361.436.camel@amd.troyhebe> <20080819134748.GC18972@redhat.com> <1219442751.3361.459.camel@amd.troyhebe> Date: Fri, 22 Aug 2008 16:48:10 -0700 In-Reply-To: <1219442751.3361.459.camel@amd.troyhebe> (Bob Montgomery's message of "Fri, 22 Aug 2008 16:05:51 -0600") Message-ID: MIME-Version: 1.0 Subject: Re: Trying to test my gart/iommu vmcore problem on RH 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-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: bob.montgomery@hp.com Cc: "Heber, Troy" , "Loftin, Terry" , Kexec Mailing List , Vivek Goyal Hmm. Thinking about this we actually have 2 problems. - Communication about what is going on. - How to handle an iommu in the event of a crash dump scenario. The current solution is to ignore the iommu, and use swiotlb. This solution does not look like it will work for future iommus. The original plan (and it still sounds like a good one) was to reserve a section of the iommu (as we do for the physical memory). So we could have addresses that are only used for the crash dump kernel. Then have the crash dump kernel just use that section of the iommu. Either we need to do that or we need to disable the iommu, before we use swiotlb. The problem is we can not reliably kill on-going DMA transactions at the time of a kernel panic, and likely doing so would greatly decrease our kernel reliability. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec