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Date:   Wed, 5 Feb 2020 08:14:46 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Jason Gunthorpe <jgg@mellanox.com>
Cc:     Jason Wang <jasowang@redhat.com>,
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Subject: Re: [PATCH] vhost: introduce vDPA based backend
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On Wed, Feb 05, 2020 at 08:56:48AM -0400, Jason Gunthorpe wrote:
> On Wed, Feb 05, 2020 at 03:50:14PM +0800, Jason Wang wrote:
> > > Would it be better for the map/umnap logic to happen inside each device ?
> > > Devices that needs the IOMMU will call iommu APIs from inside the driver callback.
> > 
> > Technically, this can work. But if it can be done by vhost-vpda it will make
> > the vDPA driver more compact and easier to be implemented.
> 
> Generally speaking, in the kernel, it is normal to not hoist code of
> out drivers into subsystems until 2-3 drivers are duplicating that
> code. It helps ensure the right design is used
> 
> Jason

That's up to the sybsystem maintainer really, as there's also some
intuition involved in guessing a specific API is widely useful.
In-kernel APIs are flexible, if we find something isn't needed we just
drop it.

-- 
MST