From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40862) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbUFf-0005LS-75 for qemu-devel@nongnu.org; Wed, 30 Oct 2013 07:48:01 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VbUFZ-00073y-6a for qemu-devel@nongnu.org; Wed, 30 Oct 2013 07:47:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30472) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VbUFY-00073s-Tb for qemu-devel@nongnu.org; Wed, 30 Oct 2013 07:47:49 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r9UBlmBh028324 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 30 Oct 2013 07:47:48 -0400 Message-ID: <5270F1DF.4020506@redhat.com> Date: Wed, 30 Oct 2013 12:47:43 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <20131024211158.064049176@amt.cnet> <20131024211249.723543071@amt.cnet> <5269B378.6040409@redhat.com> <20131025045805.GA18280@amt.cnet> <526A3152.2020603@redhat.com> <20131025195032.GA6391@amt.cnet> <526AF64E.6040404@redhat.com> <1383131275.22559.8.camel@nilsson.home.kraxel.org> In-Reply-To: <1383131275.22559.8.camel@nilsson.home.kraxel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: aarcange@redhat.com, Marcelo Tosatti , qemu-devel@nongnu.org, gleb@redhat.com, "Michael S. Tsirkin" Il 30/10/2013 12:07, Gerd Hoffmann ha scritto: > On Fr, 2013-10-25 at 23:53 +0100, Paolo Bonzini wrote: >> Il 25/10/2013 20:50, Marcelo Tosatti ha scritto: >>> On Fri, Oct 25, 2013 at 09:52:34AM +0100, Paolo Bonzini wrote: >>>> Because offsets are zero, and lengths match the RAM block lengths, you >>>> do not need any complication with aliasing. This still has to be done >>>> only for new machine types. >>> >>> Not possible because you just wasted holesize bytes (if number of >>> additional bytes due to huge page alignment is smaller than holesize, a >>> new hugepage is required, which is not acceptable). >> >> Ok. Thanks for explaining---the patch seems good with the proper >> compatibility option in the machine type. Please run the >> guest_memory_dump_analysis test in autotest too. > > As the whole thing must depend on machine type anyway for live migration > compatibility we can also simply change the memory split, i.e. map 2GB > (-M q35) or 3GB (-M pc) below 4G instead of the odd sizes (2.75 / 3.5) > we have now. For q35 it could be a possibility. For pc, I'm worried about old Windows systems that ignore all memory outside the first 4GB. They would lose 512 MB of memory. Paolo