From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: swiotlb detection should be memory hotplug aware ? Date: Thu, 22 Jul 2010 08:44:42 +0900 Message-ID: <20100722084413I.fujita.tomonori@lab.ntt.co.jp> References: <1279664097.21596.43.camel@ank32.eng.vmware.com> <20100721135750Z.fujita.tomonori@lab.ntt.co.jp> <1279732414.10874.6.camel@ank32.eng.vmware.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from sh.osrg.net ([192.16.179.4]:48062 "EHLO sh.osrg.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755340Ab0GUXoy (ORCPT ); Wed, 21 Jul 2010 19:44:54 -0400 In-Reply-To: <1279732414.10874.6.camel@ank32.eng.vmware.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: akataria@vmware.com Cc: fujita.tomonori@lab.ntt.co.jp, konrad.wilk@oracle.com, ak@linux.intel.com, lenb@kernel.org, x86@kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, petr@vmware.com On Wed, 21 Jul 2010 10:13:34 -0700 Alok Kataria wrote: > > Basically, you want to add hot-plug memory and enable swiotlb, right? > > Not really, I am planning to do something like this, > > @@ -52,7 +52,7 @@ int __init pci_swiotlb_detect(void) > > /* don't initialize swiotlb if iommu=off (no_iommu=1) */ > #ifdef CONFIG_X86_64 > - if (!no_iommu && max_pfn > MAX_DMA32_PFN) > + if (!no_iommu && (max_pfn > MAX_DMA32_PFN || hotplug_possible())) > swiotlb = 1; Always enable swiotlb with memory hotplug enabled? Wasting 64MB on a x86_64 system with 128MB doesn't look to be a good idea. I don't think that there is an easy solution for this issue though.