[Qemu-devel] Re: [PATCH] virtio-serial: pci: Allow MSI to be disabled

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Feb 12, 2010 at 06:52:38PM +0530, Amit Shah wrote:
> Michael noted we don't allow disabling of MSI for the virtio-serial-pci
> device. Fix that.
> 
> Signed-off-by: Amit Shah <amit.shah@redhat.com>
> CC: "Michael S. Tsirkin" <mst@redhat.com>

How about using a symbolic constant for -1?
We have NIC_NVECTORS_UNSPECIFIED in net.h,
generalize it to DEV_NVECTORS_UNSPECIFIED?

Acked-by: Michael S. Tsirkin <mst@redhat.com>

As a side note, I think directly allocating a ton
of vectors before some benchmark shows it's a measureable
win for serial is a mistake. But that's a subject
for another patch.

> ---
>  hw/virtio-pci.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
> index f3373ae..bcd40f7 100644
> --- a/hw/virtio-pci.c
> +++ b/hw/virtio-pci.c
> @@ -500,8 +500,8 @@ static int virtio_serial_init_pci(PCIDevice *pci_dev)
>      if (!vdev) {
>          return -1;
>      }
> -    vdev->nvectors = proxy->nvectors ? proxy->nvectors
> -                                     : proxy->max_virtserial_ports + 1;
> +    vdev->nvectors = proxy->nvectors == -1 ? proxy->max_virtserial_ports + 1
> +                                           : proxy->nvectors;
>      virtio_init_pci(proxy, vdev,
>                      PCI_VENDOR_ID_REDHAT_QUMRANET,
>                      PCI_DEVICE_ID_VIRTIO_CONSOLE,
> @@ -585,7 +585,7 @@ static PCIDeviceInfo virtio_info[] = {
>          .init      = virtio_serial_init_pci,
>          .exit      = virtio_exit_pci,
>          .qdev.props = (Property[]) {
> -            DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 0),
> +            DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, -1),
>              DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
>              DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
>              DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy, max_virtserial_ports,
> -- 
> 1.6.2.5