From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcel Apfelbaum Subject: Re: [PATCH v3 3/4] pc & q35: Add new object pc-memory-layout. Date: Wed, 23 Apr 2014 09:51:51 +0300 Message-ID: <1398235911.30055.45.camel@localhost.localdomain> References: <1395705336-22528-1-git-send-email-dslutz@verizon.com> <1395705336-22528-4-git-send-email-dslutz@verizon.com> <53550EC0.7070207@redhat.com> <535705A6.6000301@terremark.com> Reply-To: marcel.a@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <535705A6.6000301@terremark.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org To: Don Slutz Cc: xen-devel@lists.xensource.com, "Michael S. Tsirkin" , Stefano Stabellini , qemu-devel@nongnu.org, Anthony Liguori , Paolo Bonzini List-Id: xen-devel@lists.xenproject.org On Tue, 2014-04-22 at 20:13 -0400, Don Slutz wrote: > On 04/21/14 08:27, Paolo Bonzini wrote: > > Il 24/03/2014 19:55, Don Slutz ha scritto: > >> This new object has the property max-ram-below-4g. > >> > >> If you add enough PCI devices then all mmio for them will not fit > >> below 4G which may not be the layout the user wanted. This allows > >> you to increase the below 4G address space that PCI devices can use > >> (aka decrease ram below 4G) and therefore in more cases not have any > >> mmio that is above 4G. > >> > >> For example adding "-global pc-memory-layout.max-ram-below-4g=2G" to > >> the command line will limit the amount of ram that is below 4G to > >> 2G. > > > > Does Xen's firmware allow 64-bit BARs? > > Yes. But not all supported devices do. > > > I'm wondering why this is not a problem on KVM. > > > > I suspect that it is. It only shows up when you add a lot of > PCI devices either directly or via pci pass through. Also it > is more Xen focused because the default ram below 4G is > much larger so that 32 bit only guests can have a lot of ram. > > > Also, overloading -global like this isn't the best long term choice. We should get custom -machine properties in 2.1, we should use them. > > > > I may have missed this. Is this > > [PATCH V3 0/5] remove QEMUMachine indirection from MachineClass > > Or some patch that is yet to be posted? Hi Don, I posted a patch some time ago and I am going to post it again soon with some modifications: https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg00041.html Basically what matters are these lines: machine_opts = qemu_get_machine_opts(); + if (qemu_opt_foreach(machine_opts, object_set_property, current_machine, 1) < 0) { + object_unref(OBJECT(current_machine)); + exit(1); + } You create a subtype of MACHINE which has this property and it will be automatically assigned. The positive thing here is that the property is not global anymore. Thanks, Marcel > > (I did add this to qemu_machine_opts and changed to the current > way to handle: > > Subject: Re: [Qemu-devel] [PATCH 1/1] vl.c: Add pci_hole_min_size machine option. > Date: Wed, 5 Mar 2014 08:46:33 +0200 > From: Michael S. Tsirkin > To: Don Slutz > CC: , , Anthony Liguori , Stefano Stabellini > > > > On Tue, Mar 04, 2014 at 06:51:11PM -0500, Don Slutz wrote: > > On 03/04/14 17:20, Michael S. Tsirkin wrote: > > >On Tue, Mar 04, 2014 at 02:18:49PM -0500, Don Slutz wrote: > > >>On 03/04/14 11:58, Michael S. Tsirkin wrote: > > >>>On Tue, Mar 04, 2014 at 11:36:44AM -0500, Don Slutz wrote: > > >>>>On 03/04/14 02:34, Michael S. Tsirkin wrote: > > >>>>>On Thu, Feb 27, 2014 at 05:32:23PM -0500, Don Slutz wrote: > > >>>>>>This allows growing the pci_hole to the size needed. > > ... > > > Yes. Also, please find a way to only add it to > > machine types that support it, instead of ignoring it > > silently for those that don't. > > ) > > > Paolo > >