RE: [PATCH] eal: choose IOVA mode according to compilation flags

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Viacheslav Ovsiienko [mailto:viacheslavo@nvidia.com]
> Sent: Wednesday, 12 April 2023 19.20
> 
> The DPDK can be compiled to be run in IOVA VA mode with
> 'enable_iova_as_pa=false' meson option. If there is no
> explicit EAL --iova-mode parameter specified in the command
> line the rte_eal_init() tried to deduce  VA or PA mode without
> taking into account the above mentioned compile time option,
> resulting into initialization failure.
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>
> ---
>  lib/eal/linux/eal.c | 5 ++++-

This patch is close to being a bugfix. Good catch!

You could also consider another patch, logging warnings in rte_bus_get_iommu_class() [1] for the busses that want IOVA as PA when !RTE_IOVA_IN_MBUF.

[1]: https://elixir.bootlin.com/dpdk/v23.03/source/lib/eal/common/eal_common_bus.c#L224

>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
> index c37868b7f0..4481bc4ad8 100644
> --- a/lib/eal/linux/eal.c
> +++ b/lib/eal/linux/eal.c
> @@ -1080,7 +1080,10 @@ rte_eal_init(int argc, char **argv)
>  		if (iova_mode == RTE_IOVA_DC) {
>  			RTE_LOG(DEBUG, EAL, "Buses did not request a specific
> IOVA mode.\n");
> 
> -			if (!phys_addrs) {
> +			if (!RTE_IOVA_IN_MBUF) {
> +				iova_mode = RTE_IOVA_VA;
> +				RTE_LOG(DEBUG, EAL, "IOVA VA mode is forced by
> build option.\n");

Minor detail regarding conventions: "IOVA VA " -> "IOVA as VA"

> +			} else if (!phys_addrs) {
>  				/* if we have no access to physical addresses,
>  				 * pick IOVA as VA mode.
>  				 */
> --
> 2.18.1

Reviewed-by: Morten Brørup <mb@smartsharesystems.com>