From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH 0/3] Early use of boot service memory Date: Mon, 18 Nov 2013 17:32:19 -0800 Message-ID: <528ABFA3.6060905@zytor.com> References: <20131114180455.GA32212@anatevka.fc.hp.com> <20131115005049.GJ5116@anatevka.fc.hp.com> <20131115062417.GB9237@gmail.com> <5285C639.5040203@zytor.com> <20131115140738.GB6637@redhat.com> <52865CA1.5020309@zytor.com> <20131115183002.GE6637@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131115183002.GE6637@redhat.com> Sender: owner-linux-mm@kvack.org To: Vivek Goyal Cc: Yinghai Lu , Ingo Molnar , jerry.hoemann@hp.com, Pekka Enberg , Rob Landley , Thomas Gleixner , Ingo Molnar , x86 maintainers , Matt Fleming , Andrew Morton , "list@ebiederm.org:DOCUMENTATION" , "list@ebiederm.org:MEMORY MANAGEMENT" , linux-efi@vger.kernel.org, LKML List-Id: linux-efi@vger.kernel.org On 11/15/2013 10:30 AM, Vivek Goyal wrote: > > And IOMMU support is very flaky with kdump. And IOMMU's can be turned > off at command line. And that would force one to remove crahkernel_low=0. > So change of one command line option forces change of another. It is > complicated. > > Also there are very few systems which work with IOMMU on. A lot more > which work without IOMMU. We have all these DMAR issues and still nobody > has been able to address IOMMU issues properly. > Why do we need such a big bounce buffer for kdump swiotlb anyway? Surely the vast majority of all dump devices don't need it, so it is there for completeness, no? -hpa -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640Ab3KSBcw (ORCPT ); Mon, 18 Nov 2013 20:32:52 -0500 Received: from terminus.zytor.com ([198.137.202.10]:41269 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751236Ab3KSBcs (ORCPT ); Mon, 18 Nov 2013 20:32:48 -0500 Message-ID: <528ABFA3.6060905@zytor.com> Date: Mon, 18 Nov 2013 17:32:19 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Vivek Goyal CC: Yinghai Lu , Ingo Molnar , jerry.hoemann@hp.com, Pekka Enberg , Rob Landley , Thomas Gleixner , Ingo Molnar , x86 maintainers , Matt Fleming , Andrew Morton , "list@ebiederm.org:DOCUMENTATION" , "list@ebiederm.org:MEMORY MANAGEMENT" , linux-efi@vger.kernel.org, LKML Subject: Re: [PATCH 0/3] Early use of boot service memory References: <20131114180455.GA32212@anatevka.fc.hp.com> <20131115005049.GJ5116@anatevka.fc.hp.com> <20131115062417.GB9237@gmail.com> <5285C639.5040203@zytor.com> <20131115140738.GB6637@redhat.com> <52865CA1.5020309@zytor.com> <20131115183002.GE6637@redhat.com> In-Reply-To: <20131115183002.GE6637@redhat.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/15/2013 10:30 AM, Vivek Goyal wrote: > > And IOMMU support is very flaky with kdump. And IOMMU's can be turned > off at command line. And that would force one to remove crahkernel_low=0. > So change of one command line option forces change of another. It is > complicated. > > Also there are very few systems which work with IOMMU on. A lot more > which work without IOMMU. We have all these DMAR issues and still nobody > has been able to address IOMMU issues properly. > Why do we need such a big bounce buffer for kdump swiotlb anyway? Surely the vast majority of all dump devices don't need it, so it is there for completeness, no? -hpa