* [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
@ 2016-07-21 21:21 Greg Kurz
2016-07-21 21:55 ` Greg Kurz
2016-07-22 8:04 ` Cornelia Huck
0 siblings, 2 replies; 9+ messages in thread
From: Greg Kurz @ 2016-07-21 21:21 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: Cornelia Huck, Eric Blake, qemu-devel, Marcel Apfelbaum
From: Greg Kurz <gkurz@linux.vnet.ibm.com>
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 <gkurz@linux.vnet.ibm.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
---
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))) {
+ error_setg(errp, "device cannot work when both modern and legacy modes"
+ " are disabled");
+ error_append_hint(errp, "Set either disable-modern or disable-legacy"
+ " to off\n");
+ return;
+ }
+
if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
virtio_pci_modern(proxy)) {
pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-21 21:21 [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled Greg Kurz
@ 2016-07-21 21:55 ` Greg Kurz
2016-07-22 7:51 ` Marcel Apfelbaum
2016-07-22 8:04 ` Cornelia Huck
1 sibling, 1 reply; 9+ messages in thread
From: Greg Kurz @ 2016-07-21 21:55 UTC (permalink / raw)
To: Marcel Apfelbaum; +Cc: Cornelia Huck, qemu-devel, Michael S. Tsirkin
On Thu, 21 Jul 2016 23:21:16 +0200
Greg Kurz <groug@kaod.org> wrote:
> From: Greg Kurz <gkurz@linux.vnet.ibm.com>
>
> 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 <gkurz@linux.vnet.ibm.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
> 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
> ---
Marcel,
I see that Michael has comments on your patch. If you feel this patch is valuable
for 2.7, please consider carrying and pushing it, as I'm about to take a 1-month
leave.
Thanks.
--
Greg
> 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))) {
> + error_setg(errp, "device cannot work when both modern and legacy modes"
> + " are disabled");
> + error_append_hint(errp, "Set either disable-modern or disable-legacy"
> + " to off\n");
> + return;
> + }
> +
> if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
> virtio_pci_modern(proxy)) {
> pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-21 21:55 ` Greg Kurz
@ 2016-07-22 7:51 ` Marcel Apfelbaum
0 siblings, 0 replies; 9+ messages in thread
From: Marcel Apfelbaum @ 2016-07-22 7:51 UTC (permalink / raw)
To: Greg Kurz; +Cc: Cornelia Huck, qemu-devel, Michael S. Tsirkin
On 07/22/2016 12:55 AM, Greg Kurz wrote:
> On Thu, 21 Jul 2016 23:21:16 +0200
> Greg Kurz <groug@kaod.org> wrote:
>
>> From: Greg Kurz <gkurz@linux.vnet.ibm.com>
>>
>> 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 <gkurz@linux.vnet.ibm.com>
>> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
>> Signed-off-by: Greg Kurz <groug@kaod.org>
>> ---
>> 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
>> ---
>
> Marcel,
>
> I see that Michael has comments on your patch. If you feel this patch is valuable
> for 2.7, please consider carrying and pushing it, as I'm about to take a 1-month
> leave.
>
I'll be sure to take it form here, thanks for the help!
Marcel
> Thanks.
>
> --
> Greg
>
>> 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))) {
>> + error_setg(errp, "device cannot work when both modern and legacy modes"
>> + " are disabled");
>> + error_append_hint(errp, "Set either disable-modern or disable-legacy"
>> + " to off\n");
>> + return;
>> + }
>> +
>> if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
>> virtio_pci_modern(proxy)) {
>> pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
>>
>>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-21 21:21 [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled Greg Kurz
2016-07-21 21:55 ` Greg Kurz
@ 2016-07-22 8:04 ` Cornelia Huck
2016-07-22 10:11 ` Greg Kurz
1 sibling, 1 reply; 9+ messages in thread
From: Cornelia Huck @ 2016-07-22 8:04 UTC (permalink / raw)
To: Greg Kurz; +Cc: Michael S. Tsirkin, Eric Blake, qemu-devel, Marcel Apfelbaum
On Thu, 21 Jul 2016 23:21:16 +0200
Greg Kurz <groug@kaod.org> wrote:
> From: Greg Kurz <gkurz@linux.vnet.ibm.com>
>
> 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 <gkurz@linux.vnet.ibm.com>
> Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
> 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.
> + error_setg(errp, "device cannot work when both modern and legacy modes"
> + " are disabled");
> + error_append_hint(errp, "Set either disable-modern or disable-legacy"
> + " to off\n");
> + return;
> + }
> +
> if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
> virtio_pci_modern(proxy)) {
> pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-22 8:04 ` Cornelia Huck
@ 2016-07-22 10:11 ` Greg Kurz
2016-07-22 10:32 ` Cornelia Huck
0 siblings, 1 reply; 9+ messages in thread
From: Greg Kurz @ 2016-07-22 10:11 UTC (permalink / raw)
To: Cornelia Huck
Cc: Michael S. Tsirkin, Eric Blake, qemu-devel, Marcel Apfelbaum
On Fri, 22 Jul 2016 10:04:35 +0200
Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> On Thu, 21 Jul 2016 23:21:16 +0200
> Greg Kurz <groug@kaod.org> wrote:
>
> > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> >
> > 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 <gkurz@linux.vnet.ibm.com>
> > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > Signed-off-by: Greg Kurz <groug@kaod.org>
> > ---
> > 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().
> > + error_setg(errp, "device cannot work when both modern and legacy modes"
> > + " are disabled");
> > + error_append_hint(errp, "Set either disable-modern or disable-legacy"
> > + " to off\n");
> > + return;
> > + }
> > +
> > if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
> > virtio_pci_modern(proxy)) {
> > pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
> >
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-22 10:11 ` Greg Kurz
@ 2016-07-22 10:32 ` Cornelia Huck
2016-07-22 13:23 ` Greg Kurz
0 siblings, 1 reply; 9+ messages in thread
From: Cornelia Huck @ 2016-07-22 10:32 UTC (permalink / raw)
To: Greg Kurz; +Cc: Michael S. Tsirkin, Eric Blake, qemu-devel, Marcel Apfelbaum
On Fri, 22 Jul 2016 12:11:11 +0200
Greg Kurz <groug@kaod.org> wrote:
> On Fri, 22 Jul 2016 10:04:35 +0200
> Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
>
> > On Thu, 21 Jul 2016 23:21:16 +0200
> > Greg Kurz <groug@kaod.org> wrote:
> >
> > > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > >
> > > 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 <gkurz@linux.vnet.ibm.com>
> > > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > ---
> > > 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.
>
> > > + 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).
> > > + error_append_hint(errp, "Set either disable-modern or disable-legacy"
> > > + " to off\n");
The hint looks fine to me :)
> > > + return;
> > > + }
> > > +
> > > if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
> > > virtio_pci_modern(proxy)) {
> > > pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
> > >
> >
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-22 10:32 ` Cornelia Huck
@ 2016-07-22 13:23 ` Greg Kurz
2016-07-22 13:42 ` Cornelia Huck
0 siblings, 1 reply; 9+ messages in thread
From: Greg Kurz @ 2016-07-22 13:23 UTC (permalink / raw)
To: Cornelia Huck; +Cc: qemu-devel, Marcel Apfelbaum, Michael S. Tsirkin
On Fri, 22 Jul 2016 12:32:24 +0200
Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> On Fri, 22 Jul 2016 12:11:11 +0200
> Greg Kurz <groug@kaod.org> wrote:
>
> > On Fri, 22 Jul 2016 10:04:35 +0200
> > Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> >
> > > On Thu, 21 Jul 2016 23:21:16 +0200
> > > Greg Kurz <groug@kaod.org> wrote:
> > >
> > > > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > > >
> > > > 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 <gkurz@linux.vnet.ibm.com>
> > > > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > > ---
> > > > 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;
> > > >
> > >
> >
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-22 13:23 ` Greg Kurz
@ 2016-07-22 13:42 ` Cornelia Huck
2016-07-22 14:00 ` Greg Kurz
0 siblings, 1 reply; 9+ messages in thread
From: Cornelia Huck @ 2016-07-22 13:42 UTC (permalink / raw)
To: Greg Kurz; +Cc: qemu-devel, Marcel Apfelbaum, Michael S. Tsirkin
On Fri, 22 Jul 2016 15:23:19 +0200
Greg Kurz <groug@kaod.org> wrote:
> On Fri, 22 Jul 2016 12:32:24 +0200
> Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
>
> > On Fri, 22 Jul 2016 12:11:11 +0200
> > Greg Kurz <groug@kaod.org> wrote:
> >
> > > On Fri, 22 Jul 2016 10:04:35 +0200
> > > Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> > >
> > > > On Thu, 21 Jul 2016 23:21:16 +0200
> > > > Greg Kurz <groug@kaod.org> wrote:
> > > >
> > > > > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > > > >
> > > > > 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 <gkurz@linux.vnet.ibm.com>
> > > > > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > > > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > > > ---
> > > > > 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 ?
Well, that is exactly my point; users may be surprised.
>
> Do you think we should have separate checks for pcie and !pcie ?
I don't think we should overengineer this.
>
> > >
> > > > > + 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 :)
:)
I'm fine with the patch with the changed wording, as it less confusing
for the user.
<I'll be offline next week so please just attach my
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
if the only thing you change is the message>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled
2016-07-22 13:42 ` Cornelia Huck
@ 2016-07-22 14:00 ` Greg Kurz
0 siblings, 0 replies; 9+ messages in thread
From: Greg Kurz @ 2016-07-22 14:00 UTC (permalink / raw)
To: Cornelia Huck; +Cc: qemu-devel, Marcel Apfelbaum, Michael S. Tsirkin
On Fri, 22 Jul 2016 15:42:48 +0200
Cornelia Huck <cornelia.huck@de.ibm.com> wrote:
> [...]
> > > > > On Thu, 21 Jul 2016 23:21:16 +0200
> > > > > Greg Kurz <groug@kaod.org> wrote:
> > > > >
> > > > > > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > > > > >
> > > > > > 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 <gkurz@linux.vnet.ibm.com>
> > > > > > Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
> > > > > > Signed-off-by: Greg Kurz <groug@kaod.org>
> > > > > > ---
> > > > > > 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 ?
>
> Well, that is exactly my point; users may be surprised.
>
One day legacy will be hopefully buried :)
> >
> > Do you think we should have separate checks for pcie and !pcie ?
>
> I don't think we should overengineer this.
>
Agreed.
> >
> > > >
> > > > > > + 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 :)
>
> :)
>
> I'm fine with the patch with the changed wording, as it less confusing
> for the user.
>
> <I'll be offline next week so please just attach my
>
> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
>
> if the only thing you change is the message>
>
I'll do this right away as I'll be offline for 1 month starting... just after
I post v5 :)
Cheers.
--
Greg
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2016-07-22 14:01 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-07-21 21:21 [Qemu-devel] [PATCH v4] virtio-pci: error out when both legacy and modern modes are disabled Greg Kurz
2016-07-21 21:55 ` Greg Kurz
2016-07-22 7:51 ` Marcel Apfelbaum
2016-07-22 8:04 ` Cornelia Huck
2016-07-22 10:11 ` Greg Kurz
2016-07-22 10:32 ` Cornelia Huck
2016-07-22 13:23 ` Greg Kurz
2016-07-22 13:42 ` Cornelia Huck
2016-07-22 14:00 ` Greg Kurz
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