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From: "Xie, Huawei" <huawei.xie@intel.com>
To: "Ouyang, Changchun" <changchun.ouyang@intel.com>, "dev@dpdk.org"
 <dev@dpdk.org>
Thread-Topic: vring_init bug
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Date: Wed, 9 Sep 2015 03:20:16 +0000
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Subject: Re: [dpdk-dev] vring_init bug
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> -----Original Message-----
> From: Ouyang, Changchun
> Sent: Wednesday, September 09, 2015 11:18 AM
> To: Xie, Huawei; dev@dpdk.org
> Cc: Ouyang, Changchun
> Subject: RE: vring_init bug
>=20
>=20
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Xie, Huawei
> > Sent: Wednesday, September 9, 2015 11:00 AM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] vring_init bug
> >
> > static inline void
> > vring_init(struct vring *vr, unsigned int num, uint8_t *p,
> >     unsigned long align)
> > {
> >     vr->num =3D num;
> >     vr->desc =3D (struct vring_desc *) p;
> >     vr->avail =3D (struct vring_avail *) (p +
> >         num * sizeof(struct vring_desc));
> >     vr->used =3D (void *)
> >         RTE_ALIGN_CEIL((uintptr_t)(&vr->avail->ring[num]), align); }
> >
> > There is a bug in vr->used calculation. 2 bytes of used_event_idx isn't
> > considered. Would submit a fix.
> > __u16 available[num];
> > __u16 used_event_idx;
>=20
> For vring_used ring, it also misses avail_event.
>=20
> struct vring_used {
> u16 flags ;
> u16 idx ;
> struct vring_used_elem r ing [qsz] ;
> u16 avail_event ;  // this one missed in dpdk
> } ;
>=20
> It doesn't affect the offset calculation, but it will be great if you can=
 add it
> together.

No need to add this field for use vring and you couldn't because previous a=
rray is variable length.=20