Re: EDK2 ArmVirtQemu behaviour with multiple UARTs

[Peter Maydell]

On Thu, 21 Sept 2023 at 16:26, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> On Thu, Sep 21, 2023 at 11:50:20AM +0100, Peter Maydell wrote:
> > Hi; I've been looking again at a very long standing missing feature in
> > the QEMU virt board, which is that we only have one UART. One of the
> > things that has stalled this in the past has been the odd behaviour of
> > EDK2 if the DTB that QEMU passes it describes two UARTs.
>
> Note that edk2 recently got support for virtio-serial, so you can use
> that for the console and leave the uart for debug logging.  The prebuild
> edk2 binaries in qemu have been updated days ago and these already
> support for virtio-serial..

As long as EDK2 does something sensible when the DTB says "two
UARTs here and here" and it also finds a virtio-serial PCI
device, I don't mind what exactly it does. The problem here is
more that EDK2 currently does strange things when told that
the hardware is present, rather than that anybody specifically wants
EDK2 to use multiple serial outputs.

Though given there's no way to say in the DTB "use a PCI card
for your console" I think the virtio-serial approach is likely
to be awkward for users in practice.

-- PMM