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Subject: Re: [virtio-dev] [PATCH] pci: set ISR bit on config change with MSI-X
"Michael S. Tsirkin" <mst@redhat.com> writes: > config changes are slow path anyway, so we > can as well set ISR bit to help drivers detect changes. > > This allows sharing config interrupts which is what > issue reporter seems to ask for. This seems a reasonable compromise. If the device doesn't want to read ISR Status, it doesn't have to. Thanks, Rusty. > > VIRTIO-104 > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > content.tex | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/content.tex b/content.tex > index 5936154..7f1eecb 100644 > --- a/content.tex > +++ b/content.tex > @@ -1396,6 +1396,14 @@ See sections \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-speci > > The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG capability. > > +The device MUST set the Device Configuration Interrupt bit > +in \field{ISR status} before sending a device configuration > +change notification to the driver. > + > +If MSI-X capability is disabled, the device MUST set the Queue > +Interrupt bit in \field{ISR status} before sending a virtqueue > +notification to the driver. > + > If MSI-X capability is disabled, the device MUST set the Interrupt Status > bit in the PCI Status register in the PCI Configuration Header of > the device to the logical OR of all bits in \field{ISR status} of > @@ -1406,8 +1414,8 @@ The device MUST reset \field{ISR status} to 0 on driver read. > > \drivernormative{\paragraph}{ISR status capability}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / ISR status capability} > > -The driver MUST NOT access the ISR field when MSI-X capability > -is enabled. > +If MSI-X capability is enabled, the driver SHOULD NOT access > +\field{ISR status} upon detecting a Queue Interrupt. > > \subsubsection{Device-specific configuration}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Device-specific configuration} > > -- > MST > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org
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