Re: [Qemu-devel] [PATCH 0/8] Add virtio-mmio and use it in vexpress

[Andreas Färber]

Am 08.07.2013 23:06, schrieb Anthony Liguori:
> Alexander Graf <address@hidden> writes:
> 
>> On 08.07.2013, at 22:08, Anthony Liguori wrote:
>>
>>> I think we're trying to fit a square peg into a round hole.
>>>
>>> virtio-mmio is a virtio transport where each device has a dedicated set
>>> of system resources.
>>>
>>> Alex, it sounds like you want virtio-mmio-bus which would be a single
>>> set of system resources that implemented a virtio bus on top of it.
>>
>> Well, what I really want is a sysbus that behaves like PCI from a
>> usability point of view ;).
> 
> Which means you need to have (1) a discovery mechanism with a stable
> addressing mechanism (2) a way to communicate this to the guest from the
> host.

FWIW I vaguely remember a Lightning Talk at FOSDEM 2012 about MMIO
device discovery through chained in-memory data structures or so:
https://archive.fosdem.org/2012/schedule/event/wishbone.html
http://www.ohwr.org/projects/fpga-config-space

Maybe such metadata could be supplied alongside a virtual device,
whether on Wishbone, AMBA or whatever? Just a thought.

Regards,
Andreas

> That's all that PCI is.  A host controller is a "sysbus" device that
> uses a standardized discovery and addressing mechanism.
> 
> Regards,
> 
> Anthony Liguori

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