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SubjectRe: [Alacrityvm-devel] [PATCH v3 3/6] vbus: add a "vbus-proxy" bus model for vbus_driver objects
On 08/18/2009 06:53 PM, Ira W. Snyder wrote:
> So, in my system, copy_(to|from)_user() is completely wrong. There is no
> userspace, only a physical system. In fact, because normal x86 computers
> do not have DMA controllers, the host system doesn't actually handle any
> data transfer!
>

In fact, modern x86s do have dma engines these days (google for Intel
I/OAT), and one of our plans for vhost-net is to allow their use for
packets above a certain size. So a patch allowing vhost-net to
optionally use a dma engine is a good thing.

> I used virtio-net in both the guest and host systems in my example
> virtio-over-PCI patch, and succeeded in getting them to communicate.
> However, the lack of any setup interface means that the devices must be
> hardcoded into both drivers, when the decision could be up to userspace.
> I think this is a problem that vbus could solve.
>

Exposing a knob to userspace is not an insurmountable problem; vhost-net
already allows changing the memory layout, for example.

--
error compiling committee.c: too many arguments to function



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