Q on netfront/netback driver

Q on netfront/netback driver

[ravi kerur]

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Hello all,

I am trying to understand when and how netback and netfront drivers gets
instantiated and does netfront exist in domU's?

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.

Inputs appreciated.

Thanks
-RK

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Re: Q on netfront/netback driver

[ravi kerur]

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Hello All,

Just to add to my previous question, I am planning to make changes to
netfront and netback drivers and hence needed clarification on that.

In addition, I had another question on interfaces a.k.a "vif" created when
domU's are installed, I am unable to figure out which part of Xen code is
involved in this. Any pointers will be very much appreciated.

Thanks
-RK

On Sun, Jan 31, 2010 at 8:29 AM, ravi kerur <rkerur@gmail.com> 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 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.
>
> Inputs appreciated.
>
> Thanks
> -RK
>

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Re: Q on netfront/netback driver

[Konrad Rzeszutek Wilk]

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.
> 
> 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

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: Q on netfront/netback driver

[ravi kerur]

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Hi Daniel,

Please see inline [rk]

On Mon, Feb 1, 2010 at 9:37 AM, Konrad Rzeszutek Wilk <
konrad.wilk@oracle.com> 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
>
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
>
>

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Re: Q on netfront/netback driver

[Konrad Rzeszutek Wilk]

>  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

You definitly will need to modify the udev rules and potentially a bunch
of shell scripts in: xen/tools/hotplug/Linux

If you mean the source code of the kernel, look in
drivers/xen/netback/* files.
.. snip ..
> > > 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.
Ah, I was incorrect. It is CONFIG_XEN_NETDEV_BACKEND.

Re: Q on netfront/netback driver

[ravi kerur]

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Hi Konrad,

I thought Citrix Xenserver is based on Xen kernel and it inherited all of
Xen mgmt cli and other tools.

I have downloaded source code from
http://www.citrix.com/lang/English/lp/lp_1688623.asp
and have looked into product cd 1(in which I found netfront and netback
source code), product cd 4(probably tools). Unfortunately don't find
anything related to /xen/tools/hotplug... Any inputs?

Thanks
-RK

On Mon, Feb 1, 2010 at 1:16 PM, Konrad Rzeszutek Wilk <
konrad.wilk@oracle.com> wrote:

> >  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
>
> You definitly will need to modify the udev rules and potentially a bunch
> of shell scripts in: xen/tools/hotplug/Linux
>
> If you mean the source code of the kernel, look in
> drivers/xen/netback/* files.
> .. snip ..
> > > > 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.
> Ah, I was incorrect. It is CONFIG_XEN_NETDEV_BACKEND.
>

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Re: Q on netfront/netback driver

[Konrad Rzeszutek Wilk]

On Tue, Feb 02, 2010 at 08:14:53PM -0800, ravi kerur wrote:
> Hi Konrad,
> 
> I thought Citrix Xenserver is based on Xen kernel and it inherited all of
> Xen mgmt cli and other tools.

I don't know much about that product.
> 
> I have downloaded source code from
> http://www.citrix.com/lang/English/lp/lp_1688623.asp
> and have looked into product cd 1(in which I found netfront and netback
> source code), product cd 4(probably tools). Unfortunately don't find
> anything related to /xen/tools/hotplug... Any inputs?

I was refering to the open-source version of Xen:
xenbits.xensource.com/xen-unstable.hg and when it came to the kernel, to
the pvops version:
http://wiki.xensource.com/xenwiki/XenParavirtOps

Re: Q on netfront/netback driver

[Daniel Stodden]

On Tue, 2010-02-02 at 23:14 -0500, ravi kerur wrote:
> Hi Konrad,
> 
> I thought Citrix Xenserver is based on Xen kernel and it inherited all
> of Xen mgmt cli and other tools. 
> 
> I have downloaded source code from
> http://www.citrix.com/lang/English/lp/lp_1688623.asp
> and have looked into product cd 1(in which I found netfront and
> netback source code), product cd 4(probably tools). Unfortunately
> don't find anything related to /xen/tools/hotplug... Any inputs?

Backend management in XCP relies much less on hotplug scripts. Of course
there are still callbacks for backend device creation and removal on
xenbus. These events are however mainly bridged to a xenstore update
(online=yes/no). The rest is mainly handled by xapi. Main piece of code
would be xen-api/ocaml/xenops/device|hotplug.ml. Backend device shutdown
and subsequent removal is a primary example which works quite
differently.

Daniel

> Thanks
> -RK
> 
> On Mon, Feb 1, 2010 at 1:16 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
>         >  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
>         
>         
>         You definitly will need to modify the udev rules and
>         potentially a bunch
>         of shell scripts in: xen/tools/hotplug/Linux
>         
>         If you mean the source code of the kernel, look in
>         drivers/xen/netback/* files.
>         .. snip ..
>         > > > 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.
>         
>         Ah, I was incorrect. It is CONFIG_XEN_NETDEV_BACKEND.
> 

Re: Q on netfront/netback driver

[ravi kerur]

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Hi Daniel,

Thanks, its becoming clearer now. Follow-up question, is xen-api code is
open sourced? at least from the Citrix link below I don't see pointers to
xen-api. Inputs ?

Thanks
-Ravi

On Wed, Feb 3, 2010 at 9:43 AM, Daniel Stodden <daniel.stodden@citrix.com>wrote:

> On Tue, 2010-02-02 at 23:14 -0500, ravi kerur wrote:
> > Hi Konrad,
> >
> > I thought Citrix Xenserver is based on Xen kernel and it inherited all
> > of Xen mgmt cli and other tools.
> >
> > I have downloaded source code from
> > http://www.citrix.com/lang/English/lp/lp_1688623.asp
> > and have looked into product cd 1(in which I found netfront and
> > netback source code), product cd 4(probably tools). Unfortunately
> > don't find anything related to /xen/tools/hotplug... Any inputs?
>
> Backend management in XCP relies much less on hotplug scripts. Of course
> there are still callbacks for backend device creation and removal on
> xenbus. These events are however mainly bridged to a xenstore update
> (online=yes/no). The rest is mainly handled by xapi. Main piece of code
> would be xen-api/ocaml/xenops/device|hotplug.ml. Backend device shutdown
> and subsequent removal is a primary example which works quite
> differently.
>
> Daniel
>
> > Thanks
> > -RK
> >
> > On Mon, Feb 1, 2010 at 1:16 PM, Konrad Rzeszutek Wilk
> > <konrad.wilk@oracle.com> wrote:
> >         >  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
> >
> >
> >         You definitly will need to modify the udev rules and
> >         potentially a bunch
> >         of shell scripts in: xen/tools/hotplug/Linux
> >
> >         If you mean the source code of the kernel, look in
> >         drivers/xen/netback/* files.
> >         .. snip ..
> >         > > > 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.
> >
> >         Ah, I was incorrect. It is CONFIG_XEN_NETDEV_BACKEND.
> >
>
>
>

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Re: Q on netfront/netback driver

[Daniel Stodden]

On Wed, 2010-02-03 at 18:22 -0500, ravi kerur wrote:
> Hi Daniel,
> 
> Thanks, its becoming clearer now. Follow-up question, is xen-api code
> is open sourced? at least from the Citrix link below I don't see
> pointers to xen-api. Inputs ?

The xen-api code yes, as well as the accompanying patches for the
hypervisor and qemu. For other components you'd presently have to resort
to the source RPMs.

http://www.xen.org/products/cloud_source.html

Daniel