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From: "Ouyang, Changchun" <changchun.ouyang@intel.com>
To: "Xie, Huawei" <huawei.xie@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Thread-Topic: vring_init bug
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Date: Wed, 9 Sep 2015 03:18:05 +0000
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Subject: Re: [dpdk-dev] vring_init bug
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> -----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
>=20
> 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); }
>=20
> 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;

For vring_used ring, it also misses avail_event.

struct vring_used {
u16 flags ;
u16 idx ;
struct vring_used_elem r ing [qsz] ;
u16 avail_event ;  // this one missed in dpdk
} ;

It doesn't affect the offset calculation, but it will be great if you can a=
dd it together.