From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58201) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S4Ira-0002Yo-Av for qemu-devel@nongnu.org; Sun, 04 Mar 2012 16:21:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S4IrY-0005hB-9v for qemu-devel@nongnu.org; Sun, 04 Mar 2012 16:21:05 -0500 Received: from cantor2.suse.de ([195.135.220.15]:42235 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S4IrX-0005h4-W0 for qemu-devel@nongnu.org; Sun, 04 Mar 2012 16:21:04 -0500 Message-ID: <4F53DCBC.8050001@suse.de> Date: Sun, 04 Mar 2012 22:21:00 +0100 From: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= 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> <4F539C4E.2090304@suse.de> <7C5C662C-6D69-459A-90EA-246596648796@suse.de> <4F53CEB0.7030406@suse.de> <2BF15430-E518-4949-ABB7-D1095DE40340@suse.de> <4F53D127.3030206@suse.de> <1D497AA3-7C51-49A4-AA1A-5A0194EC3EE9@suse.de> In-Reply-To: <1D497AA3-7C51-49A4-AA1A-5A0194EC3EE9@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable 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: Alexander Graf Cc: Marcelo Tosatti , "qemu-devel@nongnu.org" , Avi Kivity , "anthony@codemonkey.ws" , David Gibson Am 04.03.2012 21:59, schrieb Alexander Graf: >=20 >=20 > On 04.03.2012, at 21:31, Andreas F=C3=A4rber wrote: >=20 >> Am 04.03.2012 21:25, schrieb Alexander Graf: >>> >>> >>> On 04.03.2012, at 21:21, Andreas F=C3=A4rber wrote= : >>> >>>> Am 04.03.2012 19:46, schrieb Alexander Graf: >>>>> >>>>> >>>>> On 04.03.2012, at 17:46, Andreas F=C3=A4rber wro= te: >>>>> >>>>>> Am 04.03.2012 12:53, schrieb Benjamin Herrenschmidt: >>>>>>> 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 impossib= le? >>>>>>>>> >>>>>>>>> We have yet to encounter such a case. It's not currently possib= le 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. >>>>>> >>>>>> Except for ppcemb-softmmu (1k), which is irrelevant for KVM AFAIU. >>>>>> >>>>>> Maybe just add an assert and be done with it? >>>>> >>>>> Assert for what? Linux page size of 64k is something perfectly norm= al on ppc. The hardware can always do at least 4k maps however. >>>> >>>> g_assert(TARGET_PAGE_SIZE <=3D getpagesize()) >>>> >>>> Just declare the above case as unsupported and abort if we encounter= it. >>> >>> What I'm trying to tell you is that it's the default case on book3s p= pc! ;) >> >> Exactly, which is why I'm saying just ignore the weird embedded case. = :) >=20 > [...] So you're saying 'break for ppcemb'. Hrm. Not sure that'd be all = that great for 440, since there host pagesize is still 4k, but T_P_S is 1= k. Err, 1k <=3D 4k would still be supported. The way I see it, the only case= s breaking would be ppc with host page size < 4k, and ppcemb with host page size < 1k (which I'm not aware of). Is it realistic to expect virtualizing a Mac or pSeries to work on a 1k/2k bamboo? TCG would be unaffected AFAICT. Andreas --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=C3=B6rffer; HRB 16746 AG N=C3=BC= rnberg