[dpdk-dev] [PATCH v3 07/11] linuxapp/eal: auto detect iova mode

[Hemant Agrawal]

On 7/11/2017 11:46 AM, Santosh Shukla wrote:
> - Moving late bus scanning to up..just after eal_parsing.
> - Auto detect iova mapping mode, based on the result of
>   rte_bus_scan_iommu_class.
>
> Signed-off-by: Santosh Shukla <santosh.shukla at caviumnetworks.com>
> Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> ---
>  lib/librte_eal/linuxapp/eal/eal.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
> index 2546b55e4..7b4dd70de 100644
> --- a/lib/librte_eal/linuxapp/eal/eal.c
> +++ b/lib/librte_eal/linuxapp/eal/eal.c
> @@ -799,6 +799,16 @@ rte_eal_init(int argc, char **argv)
>  		return -1;
>  	}
>
> +	if (rte_bus_scan()) {
> +		rte_eal_init_alert("Cannot scan the buses for devices\n");
> +		rte_errno = ENODEV;
> +		return -1;
> +	}
> +

The original place of the bus scan was with the following factors:
1. The bus scan requires the VFIO to be enabled atleast in dpaa2 case.
(VFIO code still need cleanup to be support non-pci cleanly). I tried 
moving it before bus_scan, this helped in bus scanning.

2. During SCAN, the bus may allocate memory to devices or for it's own 
usages.  rte_malloc or mempool is required in cases to support 
multi-process environment. (e.g. dpaa2 create dpbp or dpio device memory 
using the rte_malloc call).

Since none of the other rte library (mempool, memzone, tailq) is 
available at this point, it will create significant restriction on the 
bus scan.

We will prefer if you can re-introduce the "iova_mode" and allow the 
application choose, which mode it want to run.

This auto-detect logic may not work for many buses and it is going
to create serious restrictions on the bus_scan code.

> +	/* autodetect the iova mapping mode (default is iova_pa) */
> +	if (rte_bus_get_iommu_class() == RTE_IOVA_VA)
> +		rte_eal_get_configuration()->iova_mode = RTE_IOVA_VA;
> +
>  	if (internal_config.no_hugetlbfs == 0 &&
>  			internal_config.process_type != RTE_PROC_SECONDARY &&
>  			internal_config.xen_dom0_support == 0 &&
> @@ -896,12 +906,6 @@ rte_eal_init(int argc, char **argv)
>  		return -1;
>  	}
>
> -	if (rte_bus_scan()) {
> -		rte_eal_init_alert("Cannot scan the buses for devices\n");
> -		rte_errno = ENODEV;
> -		return -1;
> -	}
> -
>  	RTE_LCORE_FOREACH_SLAVE(i) {
>
>  		/*
>