From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [PATCH 1/1] direct mmio for passthrough - kernel part Date: Wed, 2 Apr 2008 00:38:06 +0200 Message-ID: <20080401223806.GD19189@duo.random> References: <1207050734-13166-1-git-send-email-benami@il.ibm.com> <1207050734-13166-2-git-send-email-benami@il.ibm.com> <47F238D8.7040608@qumranet.com> <47F249C3.6000300@codemonkey.ws> <47F26AD2.8000406@qumranet.com> <47F27D31.5050604@codemonkey.ws> <47F28B8B.6080707@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, allen.m.kay@intel.com, benami@il.ibm.com To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <47F28B8B.6080707@qumranet.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org On Tue, Apr 01, 2008 at 10:22:51PM +0300, Avi Kivity wrote: > It's just something we discussed, not code. Yes, the pfn_valid check should skip all refcounting for mmio regions without a struct page. But gfn_to_page can't work without a struct page, so some change will be needed there. With the reserved ram patch I didn't need to touch the gfn_to_page interface because the memmap happens to exist despite the ram is reserved in the e820 map, so I used !page_count() instead of the previously discussed !pfn_valid to skip all refcounting (reserved ram must skip the refcounting too because those ram pages can't be freed as they're not-ram as far as linux is concerned). ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace