Re: [Xen-devel] [PATCH v6 01/14] iommu: introduce the concept of BFN...

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.08.18 at 11:46, <paul.durrant@xxxxxxxxxx> wrote:
> --- a/xen/include/xen/mm.h
> +++ b/xen/include/xen/mm.h
> @@ -26,6 +26,11 @@
>   *   A linear idea of a guest physical address space. For an auto-translated
>   *   guest, pfn == gfn while for a non-translated guest, pfn != gfn.
>   *
> + * bfn: Bus Frame Number (definitions in include/xen/iommu.h)
> + *   The linear frame numbers of IOMMU address space. All initiators for 
> (i.e.
> + *   all devices assigned to) a guest share a single IOMMU address space and,
> + *   by default, Xen will ensure bfn == pfn.

The code changes are purely mechanical and hence fine, but I have
to admit I continue to struggle with the "bus" part in the name here:
I don't think it is any less ambiguous than GFN, because which bus
are you thinking about here? The (virtual) one as seen by the guest,
aiui. The physical (host) one would be at least as natural to be
indexed by such typed/named variables. I'd somehow like it to be
made explicit in the name whose view these represent. GBFN?
VBFN?

Jan



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