From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58490) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UhdHi-0002AV-SR for qemu-devel@nongnu.org; Wed, 29 May 2013 06:07:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UhdHa-0006Jy-Ui for qemu-devel@nongnu.org; Wed, 29 May 2013 06:07:10 -0400 Received: from ozlabs.org ([203.10.76.45]:56867) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UhdHa-0006Jr-Je for qemu-devel@nongnu.org; Wed, 29 May 2013 06:07:02 -0400 Date: Wed, 29 May 2013 20:06:42 +1000 From: David Gibson Message-ID: <20130529100642.GJ5489@boomeroo.fritz.box> References: <1368059472-25071-1-git-send-email-david@gibson.dropbear.id.au> <1368059472-25071-7-git-send-email-david@gibson.dropbear.id.au> <20130523112230.GE17480@redhat.com> <20130523121627.GC26259@boomeroo.fritz.box> <20130529094341.GG5489@boomeroo.fritz.box> <20130529095553.GN4472@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="DesjdUuHQDwS2t4N" Content-Disposition: inline In-Reply-To: <20130529095553.GN4472@redhat.com> Subject: Re: [Qemu-devel] [PATCH 6/8] pci: Simpler implementation of primary PCI bus List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: aliguori@us.ibm.com, qemu-devel@nongnu.org, David Gibson --DesjdUuHQDwS2t4N Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, May 29, 2013 at 12:55:53PM +0300, Michael S. Tsirkin wrote: > On Wed, May 29, 2013 at 07:43:41PM +1000, David Gibson wrote: > > On Thu, May 23, 2013 at 10:16:27PM +1000, David Gibson wrote: > > > On Thu, May 23, 2013 at 02:22:30PM +0300, Michael S. Tsirkin wrote: > > > > On Thu, May 09, 2013 at 10:31:10AM +1000, David Gibson wrote: > > > > > Currently pci_get_primary_bus() searches the list of root buses f= or one > > > > > with domain 0. But since host buses are always registered with d= omain 0, > > > > > this just amounts to finding the only PCI host bus. > > > > >=20 > > > > > This simplifies the implementation by defining the primary PCI bu= s to > > > > > be the first one registered, using a global variable to track it. > > > > >=20 > > > > > Signed-off-by: David Gibson > > > >=20 > > > > Or better: can we just fail if there is more than > > > > one root? > > >=20 > > > That might work, I'll look into doing that. > >=20 > > So, the difficulty with this is that then any machine with multiple > > PCI bridges could not use pci_nic_init(), since it calls > > pci_get_bus_devfn() which calls pci_find_primary_bus() which would > > always fail. And using pci_nic_init() is more or less mandatory in > > the machine_init function to support old-style nic configuration. > >=20 > > Suggestions? >=20 > You mean multiple PCI roots? > Well, there are no legacy machines with multiple roots to support, are > there? So why do we need to support legacy flags for these new > configurations? Because people expect them. Plus on spapr we already support the legacy nic options; it would be very strange for them to suddenly break when we add a second host bridge. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --DesjdUuHQDwS2t4N Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlGl0zIACgkQaILKxv3ab8Yt+QCgiTyUdX9PzMC3TOiPv1dhlMY5 YNMAmQGiUoFQiXWYXb77QnruZ6Ybppy7 =YqYW -----END PGP SIGNATURE----- --DesjdUuHQDwS2t4N--