From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35704) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S4APB-0000P6-Q7 for qemu-devel@nongnu.org; Sun, 04 Mar 2012 07:19:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S4APA-0003rB-1T for qemu-devel@nongnu.org; Sun, 04 Mar 2012 07:19:13 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41130) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S4AP9-0003qz-PZ for qemu-devel@nongnu.org; Sun, 04 Mar 2012 07:19:11 -0500 Message-ID: <4F535DB3.4030205@redhat.com> Date: Sun, 04 Mar 2012 14:18:59 +0200 From: Avi Kivity MIME-Version: 1.0 References: <1330043012-30556-1-git-send-email-david@gibson.dropbear.id.au> <1330043012-30556-7-git-send-email-david@gibson.dropbear.id.au> <4F4CC96B.6040003@redhat.com> <1330465707.11728.29.camel@pasglop> <4F5348CE.8070909@redhat.com> <1330861999.11728.79.camel@pasglop> In-Reply-To: <1330861999.11728.79.camel@pasglop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 6/6] kvm: Fix dirty tracking with large kernel page size List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Benjamin Herrenschmidt Cc: Marcelo Tosatti , qemu-devel@nongnu.org, anthony@codemonkey.ws, David Gibson On 03/04/2012 01:53 PM, Benjamin Herrenschmidt wrote: > On Sun, 2012-03-04 at 12:49 +0200, Avi Kivity wrote: > > On 02/28/2012 11:48 PM, Benjamin Herrenschmidt wrote: > > > On Tue, 2012-02-28 at 14:32 +0200, Avi Kivity wrote: > > > > > > > What if TARGET_PAGE_SIZE > getpagesize()? Or is that impossible? > > > > > > We have yet to encounter such a case. It's not currently possible on > > > power (some old embedded chips could do 1K and 2K page sizes in the TLB > > > iirc but we never supported that in Linux and it's being phased out in > > > HW). > > > > > > I suggest that gets dealt with when/if it needs to, which means probably > > > never :-) > > > > Doesn't ppc support both 4k and 64k pages? Suppose you run a 4k guest > > on a 64k host? > > > > Maybe I'm misremembering or misunderstanding something. > > TARGET_PAGE_SIZE in qemu is always 4k for powerpc, it's a compile time > #define. > > The host kernel exposes the dirty bit map with a bit per -host- kernel > PAGE_SIZE (which is what getpagesize() gets you in qemu). > > My patch makes thus makes things work when the host uses 64K page sizes. > In all cases, the guest page size is irrelevant, this is purely a > problem between the host kernel and qemu. Right (and I actually knew all this stuff before :( ). -- error compiling committee.c: too many arguments to function