From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Alacrityvm-devel] [PATCH v2 2/4] KVM: introduce "xinterface" API for external interaction with guests Date: Wed, 07 Oct 2009 09:43:30 +0200 Message-ID: <4ACC46A2.2090103@redhat.com> References: <20091002201159.4014.33268.stgit@dev.haskins.net> <20091002201927.4014.29432.stgit@dev.haskins.net> <4AC8780D.1060800@redhat.com> <4ACA87D7.1080206@gmail.com> <4ACB0F3C.1000705@redhat.com> <4ACB46AD.8010405@gmail.com> <4ACB6E21.8010109@redhat.com> <4ACB771E.8050404@gmail.com> <20091006181859.GD6386@ovro.caltech.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Gregory Haskins , David Howells , Gregory Haskins , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, "alacrityvm-devel@lists.sourceforge.net" To: "Ira W. Snyder" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:36545 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932223AbZJGHoM (ORCPT ); Wed, 7 Oct 2009 03:44:12 -0400 In-Reply-To: <20091006181859.GD6386@ovro.caltech.edu> Sender: kvm-owner@vger.kernel.org List-ID: On 10/06/2009 08:18 PM, Ira W. Snyder wrote: > > The limitation I have is that memory made available from the host system > (PCI card) as PCI BAR1 must not be migrated around in memory. I can only > change the address decoding to hit a specific physical address. AFAIK, > this means it cannot be userspace memory (since the underlying physical > page could change, or it could be in swap), and must be allocated with > something like __get_free_pages() or dma_alloc_coherent(). > Expose it as /dev/something (/dev/mem, /sys/.../pci/...) and mmap() it, and it becomes non-pageable user memory. Not sure about dma_alloc_coherent(), that is meaningless on x86. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.