Re: [PATCH v4 6/8] tools/xl: enable NS16550-compatible UART emulator for HVM (x86)

[Anthony PERARD <anthony@xxxxxxxxxxxxxx>]

On Mon, Aug 25, 2025 at 05:27:41PM +0200, Jan Beulich wrote:
> On 25.08.2025 17:13, Anthony PERARD wrote:
> > On Mon, Aug 25, 2025 at 05:03:40PM +0200, Jan Beulich wrote:
> >> On 25.08.2025 16:49, Anthony PERARD wrote:
> >>> On Thu, Jul 31, 2025 at 07:22:12PM +0000, dmkhn@xxxxxxxxx wrote:
> >>>> -=item B<vuart="uart">
> >>>> +=item B<vuart=[ "sbsa_uart", "ns16550" ]>
> >>>
> >>> This syntax here would inditace that `vuart` takes a list of items. You
> >>> could write instead:
> >>>
> >>>     vuart="UART"
> >>>
> >>> which seems more in line with the rest of the man page. Then you can add
> >>> some thing like "with UART been one of "sbsa_uart" or "ns16550". It's
> >>> possible to also have a sublist, like the `tee` option have.
> >>
> >> But shouldn't the syntax already now allow for multiple items? Possibly
> >> even multiple ones of the same kind?
> > 
> > How does `vuart="uart"` allow for multiple items?
> 
> Precisely. I would have expected it to be e.g.
> 
> vuart = [ "ns16550", "ns16550", "sbsa-uart" ]

This is not an option.

Having mutliple ns16550 would do exactly the same thing as having a
single one. It's not possible to have both ns16550 and sbsa_uart at the
same time, one is for x86, one is for Arm. I don't know if it's possible
to have several sbsa_uart but the code in libxl doesn't have the
capability.

So overall, I don't think having a list in the xl.cfg syntax is useful
right now. It's easy to change later, I think.

> (i.e. the square brackets are part of the necessary syntax).
> 
> Jan

-- 
Anthony PERARD