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

To: Kaushik Kumar Ram <kaushik@xxxxxxxx>
Subject: Re: [Xen-devel] Porting linux network driver to Xen
From: ravi kerur <rkerur@xxxxxxxxx>
Date: Wed, 4 Nov 2009 13:18:50 -0800
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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.



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.


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.

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