From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54182) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZyHAD-0004EK-W3 for qemu-devel@nongnu.org; Mon, 16 Nov 2015 05:37:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZyHA8-0004x8-Vg for qemu-devel@nongnu.org; Mon, 16 Nov 2015 05:37:33 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58967) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZyHA8-0004wu-QZ for qemu-devel@nongnu.org; Mon, 16 Nov 2015 05:37:28 -0500 Date: Mon, 16 Nov 2015 12:37:24 +0200 From: "Michael S. Tsirkin" Message-ID: <20151116123454-mutt-send-email-mst@redhat.com> References: <1447601946-31248-1-git-send-email-marcel@redhat.com> <5649966C.7070702@redhat.com> <5649A770.5070908@redhat.com> <5649A857.406@redhat.com> <5649A9CA.2070309@redhat.com> <5649A9F9.5070405@redhat.com> <5649AB7F.9030702@redhat.com> <5649ABDF.1010901@redhat.com> <5649B123.1050507@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5649B123.1050507@redhat.com> Subject: Re: [Qemu-devel] [PATCH V2 0/4] hw/pcie: Multi-root support for Q35 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Marcel Apfelbaum Cc: ehabkost@redhat.com, qemu-devel@nongnu.org, kraxel@redhat.com, imammedo@redhat.com, Paolo Bonzini , rth@twiddle.net On Mon, Nov 16, 2015 at 12:34:11PM +0200, Marcel Apfelbaum wrote: > On 11/16/2015 12:11 PM, Paolo Bonzini wrote: > > > > > >On 16/11/2015 11:10, Marcel Apfelbaum wrote: > >>>What would you lose? Hotplug? > >> > >>Without the bridge? Yes. However the user can add it manually the > >>pci-bridge and have it anyway. > > > >Ok, I guess that's more or less acceptable. It's still ugly however, to > >the point that I wonder if we should rename the device and call the old > >one a failed experiment. > > > > I guess we can rename the pxb to extra-root or something, but in this way > will have a deprecated/duplicated device to support and kill in the future. > > Why not use the compat property as it is? > Again, the command line *remains* the same, the difference is where the > devices associated with the pxb will land: on the secondary bus (for QEMU < 2.5) > or on the root bus itself (QEMU >= 2.5). > > I know is guest visible, but the guest will see one of them depending on the machine type. > > Regarding the splitting of pxb into 2 devices (pci/pcie), I have nothing against it, > but because the implementation is *exactly* the same I think we should gain more > by maintaining one device. > > > Thanks, > Marcel Yes, I think you want a new "pci-extender" device which is just the extender. Then existing pxb will create both it and the bridge behind it. Maybe creating pxb which is extender+bridge was a mistake, I don't know, but we shipped it in QEMU so we support it. > > >Paolo > > > >>I wanted to get rid of the internal pci-bridge as a default, and this > >>is why pxb and pxb-pcie are he same device now (except bus type)