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From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Date: Thu, 28 Jan 2016 15:40:01 +0100
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Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v6] vfio: Support for no-IOMMU mode
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2016-01-28 14:16, Burakov, Anatoly:
> Hi Thomas,
> 
> > 2016-01-28 11:57, Anatoly Burakov:
> > > +#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 5, 0)
> > 
> > Why not #ifndef VFIO_NOIOMMU_IOMMU?
> > It would avoid some backport issue.
> 
> I don't see how it could. Versions post-4.5 will have VFIO_NOIOMMU_IOMMU, so no issue there. Pre-4.5 versions, whether they do or do not have VFIO_NOIOMMU_IOMMU defined, will have RTE_VFIO_NOIOMMU defined as 8 regardless.

Are we sure it will ever be backported as 8?
Anyway I think it's better to avoid version number checks.
What happens if the feature is reverted from 4.5 as it was from 4.4?