| Message ID | 20181207084842.13133-3-tiwei.bie@intel.com |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | virtio_ring: define flags as shifts consistently | expand |
On Fri, Dec 07, 2018 at 04:48:41PM +0800, Tiwei Bie wrote: > Introduce VIRTIO_RING_NO_LEGACY to support disabling legacy > macros and layout definitions. > > Suggested-by: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: Tiwei Bie <tiwei.bie@intel.com> > --- > VRING_AVAIL_ALIGN_SIZE, VRING_USED_ALIGN_SIZE and VRING_DESC_ALIGN_SIZE > are not pre-virtio 1.0, but can also be disabled by VIRTIO_RING_NO_LEGACY > in this patch, because their names are not consistent with other names. > Not sure whether this is a good idea. If we want this, we may also want > to define _SPLIT_ version for them. I don't think it's a good idea to have alignment in there - the point of NO_LEGACY is to help catch bugs not to sanitize coding style IMHO. And spec calls "legacy" the 0.X interfaces, let's not muddy the waters. > > include/uapi/linux/virtio_ring.h | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h > index 9b0c0d92ab62..192573827850 100644 > --- a/include/uapi/linux/virtio_ring.h > +++ b/include/uapi/linux/virtio_ring.h > @@ -37,6 +37,7 @@ > #include <linux/types.h> > #include <linux/virtio_types.h> > > +#ifndef VIRTIO_RING_NO_LEGACY > /* > * Notice: unlike other _F_ flags, below flags are defined as shifted > * values instead of shifts for compatibility. > @@ -51,6 +52,7 @@ > #define VRING_USED_F_NO_NOTIFY 1 > /* Same as VRING_SPLIT_AVAIL_F_NO_INTERRUPT. */ > #define VRING_AVAIL_F_NO_INTERRUPT 1 > +#endif /* VIRTIO_RING_NO_LEGACY */ > > /* Mark a buffer as continuing via the next field in split ring. */ > #define VRING_SPLIT_DESC_F_NEXT 0 > @@ -151,6 +153,7 @@ struct vring { > struct vring_used *used; > }; > > +#ifndef VIRTIO_RING_NO_LEGACY > /* Alignment requirements for vring elements. > * When using pre-virtio 1.0 layout, these fall out naturally. > */ > @@ -203,6 +206,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) > + align - 1) & ~(align - 1)) > + sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num; > } > +#endif /* VIRTIO_RING_NO_LEGACY */ > > /* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ > /* Assuming a given event_idx value from the other side, if > -- > 2.17.1
On Fri, Dec 07, 2018 at 01:05:35PM -0500, Michael S. Tsirkin wrote: > On Fri, Dec 07, 2018 at 04:48:41PM +0800, Tiwei Bie wrote: > > Introduce VIRTIO_RING_NO_LEGACY to support disabling legacy > > macros and layout definitions. > > > > Suggested-by: Michael S. Tsirkin <mst@redhat.com> > > Signed-off-by: Tiwei Bie <tiwei.bie@intel.com> > > --- > > VRING_AVAIL_ALIGN_SIZE, VRING_USED_ALIGN_SIZE and VRING_DESC_ALIGN_SIZE > > are not pre-virtio 1.0, but can also be disabled by VIRTIO_RING_NO_LEGACY > > in this patch, because their names are not consistent with other names. > > Not sure whether this is a good idea. If we want this, we may also want > > to define _SPLIT_ version for them. > > I don't think it's a good idea to have alignment in there - the point of > NO_LEGACY is to help catch bugs not to sanitize coding style IMHO. > > And spec calls "legacy" the 0.X interfaces, let's not muddy the waters. Make sense. Thanks! > > > > > include/uapi/linux/virtio_ring.h | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h > > index 9b0c0d92ab62..192573827850 100644 > > --- a/include/uapi/linux/virtio_ring.h > > +++ b/include/uapi/linux/virtio_ring.h > > @@ -37,6 +37,7 @@ > > #include <linux/types.h> > > #include <linux/virtio_types.h> > > > > +#ifndef VIRTIO_RING_NO_LEGACY > > /* > > * Notice: unlike other _F_ flags, below flags are defined as shifted > > * values instead of shifts for compatibility. > > @@ -51,6 +52,7 @@ > > #define VRING_USED_F_NO_NOTIFY 1 > > /* Same as VRING_SPLIT_AVAIL_F_NO_INTERRUPT. */ > > #define VRING_AVAIL_F_NO_INTERRUPT 1 > > +#endif /* VIRTIO_RING_NO_LEGACY */ > > > > /* Mark a buffer as continuing via the next field in split ring. */ > > #define VRING_SPLIT_DESC_F_NEXT 0 > > @@ -151,6 +153,7 @@ struct vring { > > struct vring_used *used; > > }; > > > > +#ifndef VIRTIO_RING_NO_LEGACY > > /* Alignment requirements for vring elements. > > * When using pre-virtio 1.0 layout, these fall out naturally. > > */ > > @@ -203,6 +206,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) > > + align - 1) & ~(align - 1)) > > + sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num; > > } > > +#endif /* VIRTIO_RING_NO_LEGACY */ > > > > /* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ > > /* Assuming a given event_idx value from the other side, if > > -- > > 2.17.1
diff --git a/include/uapi/linux/virtio_ring.h b/include/uapi/linux/virtio_ring.h index 9b0c0d92ab62..192573827850 100644 --- a/include/uapi/linux/virtio_ring.h +++ b/include/uapi/linux/virtio_ring.h @@ -37,6 +37,7 @@ #include <linux/types.h> #include <linux/virtio_types.h> +#ifndef VIRTIO_RING_NO_LEGACY /* * Notice: unlike other _F_ flags, below flags are defined as shifted * values instead of shifts for compatibility. @@ -51,6 +52,7 @@ #define VRING_USED_F_NO_NOTIFY 1 /* Same as VRING_SPLIT_AVAIL_F_NO_INTERRUPT. */ #define VRING_AVAIL_F_NO_INTERRUPT 1 +#endif /* VIRTIO_RING_NO_LEGACY */ /* Mark a buffer as continuing via the next field in split ring. */ #define VRING_SPLIT_DESC_F_NEXT 0 @@ -151,6 +153,7 @@ struct vring { struct vring_used *used; }; +#ifndef VIRTIO_RING_NO_LEGACY /* Alignment requirements for vring elements. * When using pre-virtio 1.0 layout, these fall out naturally. */ @@ -203,6 +206,7 @@ static inline unsigned vring_size(unsigned int num, unsigned long align) + align - 1) & ~(align - 1)) + sizeof(__virtio16) * 3 + sizeof(struct vring_used_elem) * num; } +#endif /* VIRTIO_RING_NO_LEGACY */ /* The following is used with USED_EVENT_IDX and AVAIL_EVENT_IDX */ /* Assuming a given event_idx value from the other side, if
Introduce VIRTIO_RING_NO_LEGACY to support disabling legacy macros and layout definitions. Suggested-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com> --- VRING_AVAIL_ALIGN_SIZE, VRING_USED_ALIGN_SIZE and VRING_DESC_ALIGN_SIZE are not pre-virtio 1.0, but can also be disabled by VIRTIO_RING_NO_LEGACY in this patch, because their names are not consistent with other names. Not sure whether this is a good idea. If we want this, we may also want to define _SPLIT_ version for them. include/uapi/linux/virtio_ring.h | 4 ++++ 1 file changed, 4 insertions(+)