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[Xen-devel] extend shared_info stuct

  • To: <xen-devel@xxxxxxxxxxxxx>
  • From: Kerti Csaba <csocskos@xxxxxxxxxxx>
  • Date: Mon, 30 Jul 2012 16:24:35 +0200
  • Delivery-date: Mon, 30 Jul 2012 14:25:15 +0000
  • Importance: Normal
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>

Dear Dev Mail-list!
In my small experiment, I would like to extend the shared_info stuct of the 
hypervisor in the xen/include/public/xen.h with few variables. I already made a 
try, but I failed. I like to do this, because I want to store/read public 
values between the guests and the domain0.
I tried to add these fields to the end of the shared_info. I did “make” it and 
install it. (I avoid the size checker of the shared_info).

As I know, the guest operation system should know this modification, so I 
modified the guest op system at include/xen/interface/xen.h (ubuntu 11.04). I 
was a bit surprised because the two interface (xen.h) was not the same, even in 
the shared_info stuct there was some different (in the pvclock_wall wc 

The operation system of the domain0 should be changed as well ?? Just in case I 
made the same modification. (ubuntu 12.04)

I tried out the system with an already existing virtual machine to add it with 
the xm create with the following variables:
modified xen + modified dom0 kernel + modified guest kernel => failed to boot
modified xen + original dom0 kernel + modified guest kernel => failed to boot
modified xen + original dom0 kernel + original guest kernel => failed to boot
original xen + original dom0 kernel + original guest kernel => successfully boot
So my question is that how can I add extra fields to the shared_info?
what do I need to modify in the guest kernel?
do I need any modification in dom0?
Thank you!
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