Re: [PATCH] arm: xlnx-versal: fix virtio-mmio base address assignment

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Fri, Feb 05, 2021 at 11:18:28AM +0000, Peter Maydell wrote:
> On Fri, 5 Feb 2021 at 10:31, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> > 1/ virtio-mmio must be sysbus-device,
> 
> Yes.
> 
> > 2/ we can not sysbus-map out of main memory so private container
> > is incorrect, and Versal can not use "mr-ps-switch"?
> 
> No. If you have a sysbus device, and you want to map it somewhere
> other than into system-memory-map, you can do that: you use
> sysbus_mmio_get_region() to get the MemoryRegion*, and then map
> it into whatever container you need with memory_region_add_subregion().
>

Thanks, that matches how I thought things should work.

I wonder if virtio_mmio_bus_get_dev_path() really should be peeking into
Sysbus internals mmio[].addr?

Sysbus mmio[].addr looks like a candidate for removal if we ever get rid
of the default system_memory...

I don't have any good suggestions how to fix this. I guess we could wrap
memory_region_add_subregion() with a sysbus version of it that sets
mmio[].addr but that seems like a step backwards to me.
Perhaps there's a way fix this in virtio_mmio_bus_get_dev_path()?

Best regards,
Edgar