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RE: [Xen-devel] Dom0-DomU communication



Mapping memory pages betwen dom0 and domU can be done with a grant table, which is used heavily for paravirtualized device drivers. (Iâm fairly ignorant of the details, so maybe someone else will answer if you find that is a good direction to look.) Doing something like Unix shared memory between domU and domU has been explored by various research projects (XenSocket and google for âxen inter domain memory sharingâ for others) but I donât think anything (other than grant tables) has ever made it upstream into Xen.

 

From: Akshay Joglekar [mailto:akshayj_18@xxxxxxxxxxx]
Sent: Friday, February 19, 2010 12:53 PM
To: Dan Magenheimer; admin@xxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-devel] Dom0-DomU communication

 

So, from all your inputs I understand that the XenStore is the best way for transferring small amounts of data, while network (through something like sockets) is good for file transfers.

I was also wondering if there are is any convenient way of using shared memory (apart from XenStore) for file transfers. Like mapping memory pages from 1 domain to another?

Thanks

Akshay

--- On Fri, 19/2/10, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> wrote:


From: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Subject: RE: [Xen-devel] Dom0-DomU communication
To: admin@xxxxxxxxxxx, "Akshay Joglekar" <akshayj_18@xxxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Date: Friday, 19 February, 2010, 9:33 PM

As an example of small files being passed through Xenstore, look in the xen source tree under tools/xenballoon/xenballoond in the function send_memory_stats(),

which passes the contents of /proc/meminfo and /proc/vmstat via xenstore from a domU to dom0.  Note that the domU must have xenstore tools installed on it (which is often not installed by default).

 

Also note that this has likely never been tested with larger files or under heavy system loads, so probably shouldnât be relied on in a real production environment.  Thatâs what networks (and iSCSI and SANs and NFS) are designed for.

 

From: David [mailto:admin@xxxxxxxxxxx]
Sent: Friday, February 19, 2010 1:36 AM
To: Akshay Joglekar
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Dom0-DomU communication

 

No not really, Go through a network for that.

 

It is really designed for small amounts of data, usually configuration related.

 

In your original post you did say "in order to send simple data such as a character string.",

for this use case I would use the xenstore, although its easy to read/write to the xenstore in Linux guests, i'm not sure if the same utilities are available in Windows.

 

On 18 February 2010 23:19, Akshay Joglekar <akshayj_18@xxxxxxxxxxx> wrote:

Hi David,

Thanks for the reply. Can the XenStore also be used for transferring large amounts of data like a file? If not what can be used for file transfers between dom0 and domU?

Akshay
 

--- On Thu, 18/2/10, David <admin@xxxxxxxxxxx> wrote:


From: David <admin@xxxxxxxxxxx>
Subject: Re: [Xen-devel] Dom0-DomU communication
To: "Akshay Joglekar" <akshayj_18@xxxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Date: Thursday, 18 February, 2010, 3:51 AM

 

The Xenstore

On 17 February 2010 22:00, Akshay Joglekar <akshayj_18@xxxxxxxxxxx> wrote:

Hi all,

I want to establish communication between dom0 and domU in order to send simple data such as a character string. What is the best way to go about this?

Any help is greatly appreciated. Thanks in advance.

Akshay

 


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