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

[Hemant Agrawal]

On 7/13/2017 4:59 PM, Hemant Agrawal wrote:
> 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.
>

Is it possible that you offer a *rte_bus_pre_scan* kind of infra to 
detect the bus iommu class only. This way it will address all the concerns.

>> +    /* 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) {
>>
>>          /*
>>
>
>
>