Re: [Qemu-devel] [PATCH 2/2] hw/virtio: group virtio flags into an enum

[Marcel Apfelbaum]

On 02/10/2016 03:07 PM, Laurent Vivier wrote:
> On 10/02/2016 13:22, Marcel Apfelbaum wrote:
> > Minimizes the possibility to assign
> > the same bit to different features.
> >
> > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > ---
> >   hw/virtio/virtio-pci.h | 16 ++++++++++------
> >   1 file changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
> > index 6686b10..817bcde 100644
> > --- a/hw/virtio/virtio-pci.h
> > +++ b/hw/virtio/virtio-pci.h
> > @@ -58,6 +58,16 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
> >   #define VIRTIO_PCI_BUS_CLASS(klass) \
> >           OBJECT_CLASS_CHECK(VirtioPCIBusClass, klass, TYPE_VIRTIO_PCI_BUS)
> >
> > +enum {
> > +    VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
> > +    VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
> > +    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
> > +    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
> > +    VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
> > +    VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
> > +    VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
> > +};
>
> You can keep the "#define", doing something like this after the enum:
>
> #define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT
>
> So, if someone includes this ".h" out of qemu and wants to use some
> "#ifdef" to see if the bit is defined, it always works.
> (see for an example, /usr/include/linux/rtnetlink.h).

Thanks for the idea, but I don't think anyone would want to use those out
of qemu :)
I am also afraid that developers will forget to add it to the enum
and will still use the defines only.

> > +
> >   /* Need to activate work-arounds for buggy guests at vmstate load. */
> >   #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT  0
>
> You should remove this one too.

How did I manage to miss it? Thanks!
I'll send a v2
Marcel

> >   #define VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION \
> > @@ -65,23 +75,17 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
> >
> >   /* Performance improves when virtqueue kick processing is decoupled from the
> >    * vcpu thread using ioeventfd for some devices. */
> > -#define VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT 1
> >   #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << 
> > VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
> >
> >   /* virtio version flags */
> > -#define VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT 2
> > -#define VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT 3
> > -#define VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT 6
> >   #define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << 
> > VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
> >   #define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << 
> > VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
> >   #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
> >
> >   /* migrate extra state */
> > -#define VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT 4
> >   #define VIRTIO_PCI_FLAG_MIGRATE_EXTRA (1 << VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT)
> >
> >   /* have pio notification for modern device ? */
> > -#define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT 5
> >   #define VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY \
> >       (1 << VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT)