Re: [dpdk-dev] [PATCH] eal: pick IOVA as PA if IOMMU is not available

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 25-Jul-19 10:38 AM, Burakov, Anatoly wrote:
> On 25-Jul-19 10:35 AM, David Marchand wrote:
>> On Thu, Jul 25, 2019 at 11:31 AM Burakov, Anatoly
>> <anatoly.burakov@intel.com> wrote:
>>>
>>> On 25-Jul-19 9:05 AM, David Marchand wrote:
>>>> On Wed, Jul 24, 2019 at 6:46 PM Anatoly Burakov
>>>> <anatoly.burakov@intel.com> wrote:
>>>>>
>>>>> When IOMMU is not available, /sys/kernel/iommu_groups will not be
>>>>> populated. This is happening since at least 3.6 when VFIO support
>>>>> was added. If the directory is empty, EAL should not pick IOVA as
>>>>> VA as the default IOVA mode.
>>>>>
>>>>> We also assume that VFIO equals IOMMU, so if VFIO support is not
>>>>> compiled, we always assume IOMMU support is not available.
>>>>
>>>> Not sure I agree with this statement.
>>>> What about unknown (from eal pov) kernel drivers?
>>>
>>> Are there any cases where we can use IOVA as VA mode without having VFIO
>>> compiled?
>>
>> If a pmd relies on a kernel driver we don't know in EAL.
>> This is not the case afaik, but I'd prefer we don't mix vfio and iommu.
>>
> 
> OK, i can drop that.
> 

By the way, would kernel report IOMMU groups in that case? As in, would 
/sys/kernel/iommu_groups be populated?

-- 
Thanks,
Anatoly