Re: [PATCHv5 3/3] vhost_net: a kernel-level virtio server

[Avi Kivity]

On 09/24/2009 10:27 PM, Ira W. Snyder wrote:
> > > Ira can make ira-bus, and ira-eventfd, etc, etc.
> > >
> > > Each iteration will invariably introduce duplicated parts of the stack.
> > >
> > >        
> > Invariably?  Use libraries (virtio-shmem.ko, libvhost.so).
> >
> >      
> Referencing libraries that don't yet exist doesn't seem like a good
> argument against vbus from my point of view. I'm not speficially
> advocating for vbus; I'm just letting you know how it looks to another
> developer in the trenches.
>    

My argument is that we shouldn't write a new framework instead of fixing 
or extending an existing one.

> If you'd like to see the amount of duplication present, look at the code
> I'm currently working on.

Yes, virtio-phys-guest looks pretty much duplicated.  Looks like it 
should be pretty easy to deduplicate.

>   It mostly works at this point, though I
> haven't finished my userspace, nor figured out how to actually transfer
> data.
>
> The current question I have (just to let you know where I am in
> development) is:
>
> I have the physical address of the remote data, but how do I get it into
> a userspace buffer, so I can pass it to tun?
>    

vhost does guest physical address to host userspace address (it your 
scenario, remote physical to local virtual) using a table of memory 
slots; there's an ioctl that allows userspace to initialize that table.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/