Re: QEMU PIC indirection patch for in-kernel APIC work

[Evgeniy Polyakov <johnpol-9fLWQ3dKdXwox3rIn2DAYQ@public.gmane.org>]

On Tue, Apr 10, 2007 at 11:19:52AM +0300, Avi Kivity (avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org) wrote:
> I meant, network aio in the mainline kernel.  I am aware of the various
> out-of-tree implementations.

If potential users do not pay attention to initial implementaion, it is
quite hard to them to get into. But actually it does not matter to this
discussion.

> > But it looks from this discussion, that it will not prevent from
> > changing in-kernel driver - place a hook into skb allocation path and
> > allocate data from opposing memory - get pages from another side and put
> > them into fragments, then copy headers into skb->data.
> >   
> 
> I don't understand this (opposing memory, another side?).  Can you
> elaborate?

You want to implement zero-copy network device between host and guest, if
I understood this thread correctly?
So, for sending part, device allocates pages from receiver's memory (or
from shared memory), receiver gets an 'interrupt' and got pages from own
memory, which are attached to new skb and transferred up to the network
stack.
It can be extended to use shared ring of pages.

-- 
	Evgeniy Polyakov

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