Re: [PATCH v3 01/21] net/virtio: by default disable packed virtqueues

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 04/05/2018 12:10 PM, Jens Freimann wrote:
> Disable packed virtqueues for now and make it dependend on a build-time
> config option. This can be reverted once we have missing features like
> indirect descriptors implemented.
> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> ---
>   config/common_base                 | 1 +
>   drivers/net/virtio/virtio_ethdev.c | 4 ++++
>   2 files changed, 5 insertions(+)
> 
> diff --git a/config/common_base b/config/common_base
> index c09c7cf88..cd4b419b4 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -346,6 +346,7 @@ CONFIG_RTE_LIBRTE_VIRTIO_PMD=y
>   CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_RX=n
>   CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_TX=n
>   CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_DUMP=n
> +CONFIG_RTE_LIBRTE_VIRTIO_PQ=n
>   
>   #
>   # Compile virtio device emulation inside virtio PMD driver
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 11f758929..06fbf7311 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -1149,6 +1149,10 @@ virtio_negotiate_features(struct virtio_hw *hw, uint64_t req_features)
>   			req_features &= ~(1ULL << VIRTIO_NET_F_MTU);
>   	}
>   
> +#ifndef RTE_LIBRTE_VIRTIO_PQ
> +	req_features &= ~(1ull << VIRTIO_F_RING_PACKED);
Is VIRTIO_F_RING_PACKED already declared here?
I don't think it is, so would break build when bisecting.

Maybe the thing to do is to not have VIRTIO_F_RING_PACKED in the feature 
set by default. And when RTE_LIBRTE_VIRTIO_PQ is set, enable it and
explicitly disable indirect descs.

> +#endif
> +
>   	/*
>   	 * Negotiate features: Subset of device feature bits are written back
>   	 * guest feature bits.
>