Thanks Ben for your reply. On Tue, Apr 3, 2012 at 12:18 AM, Ben Pfaff <b...@nicira.com> wrote:
> On Sat, Mar 31, 2012 at 04:37:41PM +0800, Min Chen wrote: > > I am reading source code of Open vSwitch 1.4.0. I have a question on > > updating ports immediately upon ofproto_port_add > > This is a strange question. What prompts the question, that is, why > does it matter to you when we run it? > Sorry, I know it is weird but I am reading the source code and planning to port Open vSwitch to a hardware platform. > > I searched this mailing list and I found Ben's > > comment<http://openvswitch.org/pipermail/dev/2011-May/008561.html>on > > updating ports after port_add. Ben wrote "I don't see a reason to > > defer > > this." > > Right. That was patch 28 out of 35 in a patch series that refactored > the whole switch implementation. My guess is that the goal was not > to update the port earlier or later, but to update it in a place that > made it more amenable to refactoring in a later commit. > > > But what dose update_port do? > > It keeps the switch's knowledge of the collection of ports it manages > up to date. As an important side effect, it sends OpenFlow > OFPT_PORT_STATUS messages. > > > Since netdev is opened before calling ofproto_port_add, why it's opened > > again in update_port: > > Not all the callers have a netdev. > Sorry, but I am new to the Open vSwitch world so my questions might appear obvious to you. I am planning to port OVS to a hardware platform(a box with a switch chip connected to CPU via PCI-E interfaces). The goal is to support OpenFlow on this box. So the bonding, LACP, 802.1ag and other features are not of my concern. I've been reading the source code for a while. Although the PORTING manual is quite clear, but still I have no idea how to port this to switching ASICs. For example, on writing the netdev provider, it reads in the manual: > * Functions required to properly implement OpenFlow features. For > example, OpenFlow requires the ability to report the Ethernet > hardware address of a port. These functions must be implemented > for minimally correct operation. > There is no API of the switching chip that will get or set the Ethernet address of a port on the chip. And what does open/close (a netdev) do on a switching chip? All the ports are managed by the chip, what should the open/close of a port mean? netdev-vport.c serves as model for minimal netdev implementation. Is this implementation sufficient when porting to a hardware platform? Again, sorry for asking these trivial questions.
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