Re: [Xen-devel] [PATCH v7b 8/8] xen/arm: add dom0-less device assignment info to docs

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 10/1/19 12:30 AM, Stefano Stabellini wrote:
> +- xen,reg
> +
> +  The xen,reg property is an array of:
> +
> +    <phys_addr size guest_addr>
> +
> +  They specify the physical address and size of the device memory
> +  ranges together with the corresponding guest address to map them to.
> +  The size of `phys_addr' and `guest_addr' is determined by
> +  #address-cells, the size of `size' is determined by #size-cells, of
> +  the partial device tree.
> +  The memory will be mapped as device memory in the guest (Device-nGnRE).
> +
> +- xen,path
> +
> +  A string property representing the path in the host device tree to the
> +  corresponding device node.
> +
> +- xen,force-assign-without-iommu
> +  If present, xen,path is optional (otherwise it is always required).
I am ok with the implementation to allow xen,path to be optional. But I 
think:
  1) This is a good habit to have xen,path present in the DT because it 
acts as documentation (the user directly know the associated node in the 
host DT).
  2) It is easier to relax a binding in the future over tightening again.

  3) This avoids the multiple behavior depending on the properties present.

So I would much prefer if the document is more strict than the actual 
implementation.
Cheers,

--
Julien Grall

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