From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59800) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bQaQN-0000yf-VE for qemu-devel@nongnu.org; Fri, 22 Jul 2016 09:23:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bQaQI-0006fx-ST for qemu-devel@nongnu.org; Fri, 22 Jul 2016 09:23:30 -0400 Received: from 10.mo178.mail-out.ovh.net ([46.105.76.150]:44757) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bQaQI-0006fi-Iy for qemu-devel@nongnu.org; Fri, 22 Jul 2016 09:23:26 -0400 Received: from player169.ha.ovh.net (b9.ovh.net [213.186.33.59]) by mo178.mail-out.ovh.net (Postfix) with ESMTP id 333E91004DED for ; Fri, 22 Jul 2016 15:23:25 +0200 (CEST) Date: Fri, 22 Jul 2016 15:23:19 +0200 From: Greg Kurz Message-ID: <20160722152319.08aa16ad@bahia.lan> In-Reply-To: <20160722123224.59d0c8dd.cornelia.huck@de.ibm.com> References: <146913602256.26732.547184422534259409.stgit@bahia.lan> <20160722100435.1cf57293.cornelia.huck@de.ibm.com> <20160722121111.4626226f@bahia.lan> <20160722123224.59d0c8dd.cornelia.huck@de.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Cornelia Huck Cc: qemu-devel@nongnu.org, Marcel Apfelbaum , "Michael S. Tsirkin" On Fri, 22 Jul 2016 12:32:24 +0200 Cornelia Huck wrote: > On Fri, 22 Jul 2016 12:11:11 +0200 > Greg Kurz wrote: > > > On Fri, 22 Jul 2016 10:04:35 +0200 > > Cornelia Huck wrote: > > > > > On Thu, 21 Jul 2016 23:21:16 +0200 > > > Greg Kurz wrote: > > > > > > > From: Greg Kurz > > > > > > > > Without presuming if we got there because of a user mistake or some > > > > more subtle bug in the tooling, it really does not make sense to > > > > implement a non-functional device. > > > > > > > > Signed-off-by: Greg Kurz > > > > Reviewed-by: Marcel Apfelbaum > > > > Signed-off-by: Greg Kurz > > > > --- > > > > v4: - rephrased error message and provide a hint to the user > > > > - split string literals to stay below 80 characters > > > > - added Marcel's R-b tag > > > > --- > > > > hw/virtio/virtio-pci.c | 8 ++++++++ > > > > 1 file changed, 8 insertions(+) > > > > > > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > > > index 755f9218b77d..72c4b392ffda 100644 > > > > --- a/hw/virtio/virtio-pci.c > > > > +++ b/hw/virtio/virtio-pci.c > > > > @@ -1842,6 +1842,14 @@ static void virtio_pci_dc_realize(DeviceState *qdev, Error **errp) > > > > VirtIOPCIProxy *proxy = VIRTIO_PCI(qdev); > > > > PCIDevice *pci_dev = &proxy->pci_dev; > > > > > > > > + if (!(virtio_pci_modern(proxy) || virtio_pci_legacy(proxy))) { > > > > > > I'm not sure that I didn't mess up the sequence of the realize > > > callbacks, but could disable_legacy still be AUTO here? In that case, > > > we'd fail for disable-modern=on and disable-legacy unset (i.e., AUTO), > > > which would be ok for pcie but not for !pcie. > > > > > > > Marcel made the same comment in: > > > > https://lists.gnu.org/archive/html/qemu-devel/2016-07/msg05225.html > > > > If the user explicitly disables modern, she shouldn't rely on QEMU > > implicitly enabling legacy, hence the suggestion in error_append_hint(). > > I don't know, I'd find that a bit surprising, especially as I would end > up with a legacy-capable device if I did not specify anything in > the !pcie case. > Isn't it already what happens with legacy being the default in pre-2.7 QEMU ? Do you think we should have separate checks for pcie and !pcie ? > > > > > > + error_setg(errp, "device cannot work when both modern and legacy modes" > > > > + " are disabled"); > > Suggest to change this wording to: > > "device cannot work as neither modern nor legacy mode is enabled" > > as this more accurately reflects what happened (the user did not > actively disable legacy in the case above). > Thanks ! This is THE wording I was looking for :) > > > > + error_append_hint(errp, "Set either disable-modern or disable-legacy" > > > > + " to off\n"); > > The hint looks fine to me :) > It was the easy part :) > > > > + return; > > > > + } > > > > + > > > > if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) && > > > > virtio_pci_modern(proxy)) { > > > > pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS; > > > > > > > > > > >