Hi,

On 8/30/2018 3:13 PM, Gaëtan Rivet wrote:

Hi,

On Thu, Aug 30, 2018 at 10:09:04AM +0100, Burakov, Anatoly wrote:

quoted

On 29-Aug-18 4:58 PM, eric zhang wrote:

quoted

This patch adds a configuration option to force the IOVA mode to
physical address (PA). There exists virtual devices that are not
directly attached to the PCI bus, and therefore the auto detection
of the IOVA mode based on probing the PCI bus and IOMMU configuration
may not report the required addressing mode. Having the configuration
option permits the mode to be explicitly configured in this scenario.

Signed-off-by: eric zhang <redacted>
---

Defining this at compile-time seems like an overkill. Wouldn't it be better
to just add an EAL command-line option to force IOVA mode to a particular
value?

That is a good suggestion.

quoted

-- 
Thanks,
Anatoly

What is the bus of these devices and why not implement get_iommu_class
in it?

There are cases, where you are using dpdk libraries with external 
libraries and you need to change the default behavior DPDK lib to use 
physical address instead of virtual address.
Providing an option to user will help.