XEN: Interdomain communication.

XEN: Interdomain communication.

[cooldharma06]

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hi all,

i am experimenting interdomain communication between dom0 and domU in
xen-4.2.1.

in domU i copied required libraries and also xenfs is mounted.

but in /dev/xen i have only gntdev file. but we have evtchn, gntalloc files
for communication. how i can make(create) those files for domU.

Information regarding to the communication as follows:
1. In ldd vchan-node1 shows following outputs:
10:/usr/src/xen-4.2.1/tools/libvchan# ldd vchan-node1
linux-gate.so.1 =>  (0xb7727000)
libxenvchan.so.1.0 => /usr/lib/libxenvchan.so.1.0 (0xb7717000)
libc.so.6 => /lib/libc.so.6 (0xb75d2000)
libxenstore.so.3.0 => /usr/lib/libxenstore.so.3.0 (0xb75c9000)
libxenctrl.so.4.2 => /usr/lib/libxenctrl.so.4.2 (0xb75a3000)
/lib/ld-linux.so.2 (0xb7728000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb758a000)
libdl.so.2 => /lib/libdl.so.2 (0xb7586000)

and when running that one it shows:
libxenvchan_*_init: No such file or directory

2. The files under /dev/xen/ folder in domU is : gntdev

3. The files under /proc/xen/ folder in domU is : capabilities  xenbus

Please guide me to achieve the communication.

regards,
cooldharma06.

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Re: XEN: Interdomain communication.

[Ian Campbell]

On Tue, 2013-08-20 at 16:14 +0530, cooldharma06 wrote:


> and when running that one it shows:

How exactly are you "running that". What options are you giving it?

Fwd: XEN: Interdomain communication.

[cooldharma06]

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hi,

i runned this one in domU:
./vchan-node1 client read 0 /check-path

after running this one i got the error.

by this link:
http://www.gossamer-threads.com/lists/xen/devel/284791?do=post_view_threaded#284791

i understood that /dev/xen/gntalloc, /dev/xen/gntdev, /dev/xen/gntdev files
are necessary for intervm communication. but in my domU i am having only
gntdev file only ( under /dev/xen folder).

If it requires i will send the screenshots also. guide me to achieve the
communication between dom0 to domU.

Regards,
cooldharma06.


On Tue, Aug 20, 2013 at 6:37 PM, Ian Campbell <Ian.Campbell@citrix.com>wrote:

> On Tue, 2013-08-20 at 16:14 +0530, cooldharma06 wrote:
>
>
> > and when running that one it shows:
>
> How exactly are you "running that". What options are you giving it?
>
>
>
>

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Re: Fwd: XEN: Interdomain communication.

[Ian Campbell]

On Tue, 2013-08-20 at 18:56 +0530, cooldharma06 wrote:
> hi,
> 
> 
> i runned this one in domU: 
> ./vchan-node1 client read 0 /check-path

What did you run on the server side?

I think you need to create the xenstore path you are using and give it
appropriate permissions. Since /local/domain/N/data exists and is
writable by domain N you can use "data/foo". I don't expect
"/check-path" either exists or has the correct permissions.

http://lists.xen.org/archives/html/xen-devel/2013-06/msg00061.html has
(down at the end in the quoted stuff) an example of what worked for me.
Which was:
> domU# vchan-node1 server read 0 data/vchan
>
> dom0# domU=$(xl domid d32-1)
> dom0# vchan-node1 client write ${domid} /local/domain/${domid}/data/vchan
> 
> Now I can type into the dom0 window and the data appears on the domU
> end. I can also invert the read/write parameter and go the other way.
> This demo code doesn't appear to be bidirectional.
> 
> Running the server in dom0 didn't initially work for me, because
> dom0's domid node is missing. However this was easy to work around:
> 
> dom0# xenstore-write /local/domain/0/domid 0
> dom0# domU=$(xl domid d32-1)
> dom0# vchan-node1 server read $(xl domid d32-1) data/vchan
> 
> domU# vchan-node1 client write 0 /local/domain/0/data/vchan
>
Ian

Re: XEN: Interdomain communication.

[Daniel De Graaf]

On 08/20/2013 06:44 AM, cooldharma06 wrote:
> hi all,
>
> i am experimenting interdomain communication between dom0 and domU in
> xen-4.2.1.
>
> in domU i copied required libraries and also xenfs is mounted.
>
> but in /dev/xen i have only gntdev file. but we have evtchn, gntalloc files
> for communication. how i can make(create) those files for domU.

Load the kernel modules for these files (xen-evtchn and xen-gntalloc).

You may also need to select a xenstore path with the proper permissions, as Ian
suggested in his emails. You could also use xenstore-mkdir and xenstore-chmod
in dom0 if you have a need to use a specific xenstore path.

The vchan-node2 tool may be more friendly to testing since it is bidirectional
while vchan-node1 forces you to specify read/write on each end.

> Information regarding to the communication as follows:
> 1. In ldd vchan-node1 shows following outputs:
[...]
> and when running that one it shows:
> libxenvchan_*_init: No such file or directory
>
> 2. The files under /dev/xen/ folder in domU is : gntdev
>
> 3. The files under /proc/xen/ folder in domU is : capabilities  xenbus
>
> Please guide me to achieve the communication.
>
> regards,
> cooldharma06.

-- 
Daniel De Graaf
National Security Agency