From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753294AbYIJQi5 (ORCPT ); Wed, 10 Sep 2008 12:38:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751028AbYIJQis (ORCPT ); Wed, 10 Sep 2008 12:38:48 -0400 Received: from gw.goop.org ([64.81.55.164]:32824 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751148AbYIJQis (ORCPT ); Wed, 10 Sep 2008 12:38:48 -0400 Message-ID: <48C7F80C.6000807@goop.org> Date: Wed, 10 Sep 2008 09:38:36 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: Avi Kivity CC: Ingo Molnar , Xen Devel , Andi Kleen , linux-kernel@vger.kernel.org, "H. Peter Anvin" Subject: Re: [Xen-devel] Re: [PATCH 1 of 7] x86: add _PAGE_IOMAP pte flag for IO mappings References: <4d93ba619c716c45cca0.1220826073@localhost> <48C67AE0.5060503@qumranet.com> <48C68C6B.7030803@goop.org> <48C68EA3.4050508@qumranet.com> <48C7998D.1030408@qumranet.com> In-Reply-To: <48C7998D.1030408@qumranet.com> X-Enigmail-Version: 0.95.7 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 Avi Kivity wrote: > Actually it's more of a "no struct page" flag, which implies no > refcounting. Hm, is that actually true enough to define it? Could we rename it something like _PAGE_NOSTRUCTPAGE or something a bit more specific than "special"? > And not having a struct page should correspond well to a pte not > requiring pfn->mfn conversion and being an I/O page. But _PAGE_SPECIAL is only set in a few places. It's not set in ioremap mappings and so on. Should it be? There's also the hiccup that it gets set in a pte with pte_mkspecial() - but at that point its too late because you've already constructed the pte and done the pfn->mfn conversion. _PAGE_IOMAP can only be set when you initially construct the pte out of a frame number and a pgprot. J