Page table updates

Page table updates

[Lakshitha Harshan]

Hi,

Is there a way to update the guest memory segment which points to
kernel code segment of a guest from dom0?

For example if i am running two Squeeze VMs (1,2) and if I want to
change the mappings which points kernel_ code segment of second VM to
kernel code segment of first VM, is there a way to alter memory
addresses from dom0?

Thanks,
Harshan

Re: Page table updates

[Tim Deegan]

Hi, 

At 13:22 +0530 on 30 May (1306761721), Lakshitha Harshan wrote:
> Is there a way to update the guest memory segment which points to
> kernel code segment of a guest from dom0?

You can change the guest's segment register contents using the
get/set_vcpucontext calls, but I suspect that's not what you want. 

> For example if i am running two Squeeze VMs (1,2) and if I want to
> change the mappings which points kernel_ code segment of second VM to
> kernel code segment of first VM, is there a way to alter memory
> addresses from dom0?

I don't think so - segmentation only turns virtual adresses into linear
addresses, and all the linear addresses in a given process are the same
regardless of what segment you accessed them through.  So to cause CS:
accesses to see different memory from DS: accesses I think you'd need to
emulate every instruction.

Cheers,

Tim.

-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)