Re: [Xen-devel] Porting linux network driver to Xen

[ravi kerur <rkerur@xxxxxxxxx>]

I am confused now, probably I should ask what changes are needed such that I can access NIC from guest domains(domUs) for Tx and Rx?  i.e if I compile native linux driver and run on dom0, how can I access it from domU's

are the changes just the configuration such that path is setup from domU/netfront -> dom0/netback->Bridge->NIC?

Inputs appreciated.

Thanks
-Ravi

On Wed, Nov 4, 2009 at 1:47 PM, Kaushik Kumar Ram <kaushik@xxxxxxxx> wrote:

Again, you don't have to make any changes to the driver. Netback/netfront do not interact directly with the

NIC's driver. 

-Kaushik

On Nov 4, 2009, at 3:18 PM, ravi kerur wrote:

Thanks kaushik, How does netfront/netback interact with this driver? I believe I need netback functionality running in dom0 and netfront running in domU's for the existing driver.  One of the documents has following explanation for Tx/Rx path.

"For transmit (TX) requests the driver domain(dom0) uses a hypercall to map the guest page(domU) into its address space before sending the request through the bridge. When the physical device driver frees the page a callback function is automatically invoked to return a response to netfront which then revokes the grant.

For RX requests netfront posts I/O buffer page grants to the RX I/O channel. When netback receives a packet from the bridge it retrieves a posted grant from the I/O channel and issues a grant copy hypercall to copy the packet to the guest page(domU). Finally, netback sends a response to the guest via the RX channel indicating a packet is available."

I am not quite sure what changes or api's I need to call such that existing Tx/Rx buffers(rings) used for DMA in the native drivers starts talking via netfront/netback.

Inputs appreciated.

Thanks
-RK

---

 

On Wed, Nov 4, 2009 at 8:58 AM, Kaushik Kumar Ram <kaushik@xxxxxxxx> wrote:

Native Linux drivers should work as such in Dom0. You don't have to port them.

-Kaushik

On Nov 4, 2009, at 7:17 AM, ravi kerur wrote:

Hi All,

I am working on porting an existing network driver from Linux to Xen, I understand network drivers needs netback and netfront functionality in order to work in Xen but I am unable to nail down the details of changes required esp.

a. will the existing driver go into hypervisor or dom0?
b. what changes are required in TX/RX rings for DMA in existing driver and how to incorporate them into netback/netfront,
c. handling IRQs...

Any pointers to existing nic driver or pointer to a document would be really helpful.

Thanks
-RK

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