Re: [Xen-devel] Q on netfront/netback driver

[ravi kerur <rkerur@xxxxxxxxx>]

Hi Daniel,

Please see inline [rk]

On Mon, Feb 1, 2010 at 9:37 AM, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:

On Sun, Jan 31, 2010 at 08:29:04AM -0800, ravi kerur wrote:
> Hello all,
>
> I am trying to understand when and how netback and netfront drivers gets
> instantiated and does netfront exist in domU's?

I would recommend you look in the source code to understand its
handshake mechanism. Or better yet, pick up the 'Definitive Guide to the
Xen hypervisor".

Netfront will exist in DomU's if it is compiled in or as a module
depending on the distro.

[rk] I have gone through code for netfront and netback drivers and have some understanding w.r.t their communication i.e both the drivers watch for "vif" interface creation and go through xenbus state-machine to proceed to connected state and use event-channel, shared-memory rings to communicate later on. I will look into it whether netfront/netback compiled or added as a module.

 In addition, I had follow-up question on creation of "vif" interface(this is what I was referring to when I mentioned about instantiation of netfront/netback), if I were to change this "vif" name to something else, which part of the code should be modified. I have been searching for this and have been futile so far. Inputs appreciated.

Thanks
-RK

>
> I do see the drivers available in following directory in dom0 but nothing in
> domU...
>
>  $ pwd
> /lib/modules/2.6.18-128.1.6.el5.xs5.5.0.496.1012xen/kernel/drivers/xen
>
> $ ls
> pciback  scsiback  scsifront  sfc_netback  sfc_netfront  sfc_netutil
> tpmback
>
> However, I do not see the drivers listed when "lsmod" is executed on dom0 or
> domU.

It might be very well compiled in, at which point it is not a module.
Look in your .config file for NETBACK.
>
> Inputs appreciated.
>
> Thanks
> -RK

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