07/04/2021 09:47, Maxime Coquelin:
>
> On 3/17/21 6:40 AM, Cheng Jiang wrote:
> > We use ioat ring space for determining if ioat callbacks can enqueue a
> > packet to ioat device. But there is one slot can't be used in ioat
> > ring due to the ioat driver design, so we need to reduce one slot in
> > ioat ring to prevent ring size mismatch in ioat callbacks.
> >
> > Fixes: 2aa47e94bfb2 ("examples/vhost: add ioat ring space count and check")
> > Cc: sta...@dpdk.org
> >
> > Signed-off-by: Cheng Jiang <cheng1.ji...@intel.com>
> > ---
> > examples/vhost/ioat.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c
> > index 60b73be93..9cb5e0d50 100644
> > --- a/examples/vhost/ioat.c
> > +++ b/examples/vhost/ioat.c
> > @@ -113,7 +113,7 @@ open_ioat(const char *value)
> > goto out;
> > }
> > rte_rawdev_start(dev_id);
> > - cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE;
> > + cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE - 1;
>
> That really comforts me in thinking we need a generic abstraction for
> DMA devices. How is the application developer supposed to know that
> the DMA driver has such weird limitations?
Having a generic DMA API may be interesting.
Do you know any other HW candidate for such an API?
Do you think rte_memcpy can be used as a SW driver?
