From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:42158)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1bhtit-0002ee-GK
	for qemu-devel@nongnu.org; Thu, 08 Sep 2016 03:26:12 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1bhtip-0005PL-JB
	for qemu-devel@nongnu.org; Thu, 08 Sep 2016 03:26:11 -0400
Received: from mx1.redhat.com ([209.132.183.28]:53194)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1bhtip-0005P5-EK
	for qemu-devel@nongnu.org; Thu, 08 Sep 2016 03:26:07 -0400
Message-ID: <1473319565.6698.18.camel@redhat.com>
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 08 Sep 2016 09:26:05 +0200
In-Reply-To: <31ce90c6-8775-dd71-5aaa-ead4a4b24733@redhat.com>
References: <1472736127-18137-1-git-send-email-marcel@redhat.com>
	<6c9103e7-70ad-55c6-5533-d6d9bbaa39b4@redhat.com>
	<1473161728.31857.20.camel@redhat.com>
	<4cabe465-75bc-434b-be4f-c9a4b915f435@redhat.com>
	<1473231880.28663.34.camel@redhat.com>
	<31ce90c6-8775-dd71-5aaa-ead4a4b24733@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Mime-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH RFC] docs: add PCIe devices placement
 guidelines
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Laine Stump <laine@redhat.com>
Cc: qemu-devel@nongnu.org, Laszlo Ersek <lersek@redhat.com>, Marcel Apfelbaum <marcel@redhat.com>, mst@redhat.com, Peter Maydell <peter.maydell@linaro.org>, Drew Jones <drjones@redhat.com>, Andrea Bolognani <abologna@redhat.com>, Alex Williamson <alex.williamson@redhat.com>

  Hi,

> I had understood that the xhci could be a legacy PCI device or a PCI=20
> Express device depending on the socket it was plugged into (or was that=
=20
> possibly just someone doing some hand-waving over the fact that=20
> obscuring the PCI Express capabilities effectively turns it into a=20
> legacy PCI device?).

That is correct, it'll work both ways.

> If that's the case, why do you prefer the default=20
> USB controller to be added in a root-port rather than as an integrated=
=20
> device (which is what we do with the group of USB2 controllers, as well=
=20
> as the primary video device)

Trying to mimic real hardware as close as possible.  The ich9 uhci/ehci
controllers are actually integrated chipset devices.  The nec xhci is a
express device in physical hardware.

That is more a personal preference though, there are no strong technical
reasons to do it that way.

cheers,
  Gerd