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Re: [Xen-devel] ioctl and Xen

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] ioctl and Xen
From: Kuriakose Mathew <kmathew123@xxxxxxxxx>
Date: Sat, 8 Aug 2009 16:27:23 +0530
Cc: Derek Riley <derek.riley@xxxxxxxxxxxxxxxxxxx>
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   Even I am looking for something similar. I came upon xenstore , through which we can write a particular value to a key and then read the corresponding value. Even there is a concept of watch in xenstore which gives a notification as to ,a value corresponding to a key has changed. But I could read and write only from the userspace. If you could read a key's value from kernel space , you are done. If you get anything in this direction do inform.


On Sat, Aug 8, 2009 at 2:29 AM, Derek Riley <derek.riley@xxxxxxxxxxxxxxxxxxx> wrote:
Thanks for the suggestion.  It appears to me that the xentrace only implements one-way communication between the kernel and user space, but I need 2 way communication. 

I know it is not the "right" way to do it, but is there a way to read/write a file within the scheduler?  I am working on a 1-off implementation for a specialized project that will never make it into the main kernel. 


On Fri, Aug 7, 2009 at 3:22 PM, Dulloor <dulloor@xxxxxxxxx> wrote:
You can look at the way trace-bufs are implemented in xentrace. You will find xentrace in xen/tools.


On Fri, Aug 7, 2009 at 3:36 PM, Derek Riley <derek.riley@xxxxxxxxxxxxxxxxxxx> wrote:
Thanks for your reply.  I am familiar with the files you listed, but they do not do what I need, nor do I see how they could be modified to do what I want (although I may be missing something). 

I am trying to pass simple information in and out of the scheduler while it is running to a user process for monitoring and control.  I just need an IPC method that is fast so it won't bog down the scheduler or the user space process.  Any thoughts?  Thanks

On Fri, Aug 7, 2009 at 2:29 PM, Marco Tizzoni <marco.tizzoni@xxxxxxxxx> wrote:
On Fri, Aug 7, 2009 at 7:54 PM, Derek
Riley<derek.riley@xxxxxxxxxxxxxxxxxxx> wrote:
> Hello developers-
> I am trying to modify the Xen Hypervisor kernel to pass information to and
> from a user space program to the domain scheduler (sched_credit),

I'm not experienced but I think you could have a look at:



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