From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from e28smtp06.in.ibm.com ([59.145.155.6] helo=e28esmtp06.in.ibm.com) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1KnZSB-0002oN-VR for kexec@lists.infradead.org; Wed, 08 Oct 2008 13:51:52 +0000 Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by e28esmtp06.in.ibm.com (8.13.1/8.13.1) with ESMTP id m98DpmkI003413 for ; Wed, 8 Oct 2008 19:21:48 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m98DpmjF954502 for ; Wed, 8 Oct 2008 19:21:48 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.13.1/8.13.3) with ESMTP id m98Dpm5p015985 for ; Thu, 9 Oct 2008 00:51:48 +1100 Message-ID: <48ECBAF5.5010309@in.ibm.com> Date: Wed, 08 Oct 2008 19:21:49 +0530 From: Chandru MIME-Version: 1.0 Subject: Re: kdump: quad core Opteron References: <48EB5B68.8010401@in.ibm.com> <20081007132401.GA4007@redhat.com> <1223395191.2215.179.camel@amd.troyhebe> In-Reply-To: <1223395191.2215.179.camel@amd.troyhebe> 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: "kexec@lists.infradead.org" , Vivek Goyal Bob Montgomery wrote: > Here's the README for the patch: > > This patch changes the initialization of the GART (in > pci-gart.c:init_k8_gatt) to set the DisGartCpu bit in the GART Aperture > Control Register. Setting the bit Disables requests from the CPUs from > accessing the GART. In other words, CPU memory accesses within the > range of addresses in the aperture will not cause the GART to perform an > address translation. The aperture area was already being unmapped at > the kernel level with clear_kernel_mapping() to prevent accesses from > the CPU, but that kernel level unmapping is not in effect in the kexec'd > kdump kernel. By disabling the CPU-side accesses within the GART, which > does persist through the kexec of the kdump kernel, the kdump kernel is > prevented from interacting with the GART during accesses to the dump > memory areas which include the address range of the GART aperture. > Although the patch can be applied to the kdump kernel, it is not > exercised there because the kdump kernel doesn't attempt to initialize > the GART. > > Bob Montgomery > working at HP > > I made the following changes and it seems like it is working. --- linux-2.6.27-rc8/include/asm-x86/gart.h.orig 2008-10-08 09:41:23.000000000 -0400 +++ linux-2.6.27-rc8/include/asm-x86/gart.h 2008-10-08 09:44:35.000000000 -0400 @@ -42,7 +42,8 @@ static inline void enable_gart_translati /* Enable GART translation for this hammer. */ pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &ctl); ctl |= GARTEN; - ctl &= ~(DISGARTCPU | DISGARTIO); + ctl |= DISGARTCPU; + ctl &= ~(DISGARTIO); pci_write_config_dword(dev, AMD64_GARTAPERTURECTL, ctl); } The system doesn't reset now while copying /proc/vmcore. Thanks! Chandru _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec