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To: "Tan, Jianfeng" <jianfeng.tan@intel.com>,
 Jerin Jacob <jerin.jacob@caviumnetworks.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
 "Richardson, Bruce" <bruce.richardson@intel.com>,
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 Santosh Shukla <santosh.shukla@caviumnetworks.com>
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From: Ferruh Yigit <ferruh.yigit@intel.com>
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Date: Wed, 1 Nov 2017 11:31:34 -0700
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Subject: Re: [dpdk-dev] [PATCH] eal: disable IOVA mode detection by default
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On 11/1/2017 1:53 AM, Tan, Jianfeng wrote:
> 
> 
>> -----Original Message-----
> ...
>>>
>>>> Regarding the KNI crash, it can be avoid by first checking the exiting
>>>> mode(rte_eal_iova_mode()). i.e since legacy driver like KNI need real
>>>> physical address to work "now", it can grace full exit on the init time if
>>>> mode == IOVA_VA;
>>>
>>> For the KNI crash, do we really need to correct the case:  make those PMDs
>>> (requires IOVA_VA)  also work well with KNI?
>>> - If no, we just need to report  RTE_PCI_DRV_IOVA_AS_VA smartly.
>>> - If yes, we shall make KNI work with VA.
>>
>> I would say "yes". But for this immediate release, I would say "no".
> 
> Ferruh, if you also agree on "no" for now, we might fix it like this:

I agree with Jerin, for this release "no", for long term "yes".

> 
> For PMDs like ixgbe/i40e/..., we detect if phys_addrs_available to decide RTE_PCI_DRV_IOVA_AS_VA in a RTE_INIT function.
> 
> How do you think of that?

Instead Santosh's suggestion looks simpler.
Detect if kni module inserted, if so set IOVA PA mode.

I guess rte_bus_get_iommu_class() can updated for this check as workaround.

> 
> Thanks,
> Jianfeng
>