From: Ingo Molnar Subject: Re: [PATCH 00 of 14] swiotlb/x86: lay groundwork for xen dom0 use of swiotlb Date: Thu, 18 Dec 2008 22:02:31 +0100 Message-ID: <20081218210231.GB24271@elte.hu> References: <20081216203513.GA14787@elte.hu> <20081217142637V.fujita.tomonori@lab.ntt.co.jp> <4949296F.7000701@goop.org> <20081218015705Z.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Becky Bruce Cc: Jeremy Fitzhardinge , xen-devel@lists.xensource.com, ian.campbell@citrix.com, joerg.roedel@amd.com, x86@kernel.org, Linux Kernel Mailing List , FUJITA Tomonori , Benjamin Herrenschmidt List-Id: xen-devel@lists.xenproject.org * Becky Bruce wrote: >> Can you be more specific? What architecture is plan to use highmem >> support in swiotlb? > > 32-bit powerpc needs this support - I was actually about to push a > similar set of patches. We have several processors that support 36 bits > of physical address space and do not have any iommu capability. The > rest of the kernel support for those processors is now in place, so > swiotlb is the last piece of the puzzle for that to be fully functional. > I need to take a closer look at this series to see exactly what it's > doing and how it differs from what I've been testing. > > So there is another immediate use case, and I'd really hate to see this > code duplicated. It should be entirely possible to remove the > assumption that we can save off the VA of the original buffer, which is > the thing that precludes HIGHMEM support, and still have nice readable, > maintainable code. you can have a look at Jeremy's current lineup of patches in tip/core/iotlb: http://people.redhat.com/mingo/tip.git/README (also integrated into tip/master) What would be needed to make it suit your usecase too? Ingo