Re: vio9p vs. GENERIC.local vs. XEN3_DOM[0U]

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> The right level of abstraction is to do something that says

>   if there is a virtio bus, add viop* at virtio*

> and this is true of pretty much anything that attaches to a bus that
> may or may not present.

> I wonder if there are good reasons to avoid "just skip lines that
> refer to a bus that don't exist".

My answer is, error-checking.  If I, say, typo "pci" as "cpi" in

	mydev* at cpi?

I'd want an error rather than having the line silently ignored.  (That
particular typo is not all that plausible.  It's just an example.)

Now, if virtio were specifically declared as "this name is valid but
may or may not be present"?  I'm on the fence.

If virtio were declared normally in the kernels that provide it and
declared as valid but specifically absent in XEN3_DOM* kernels?  Then I
think that's what I'd want (to my limited understanding, this is close
to what "no virtio" does at present).

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