Re: [Xen-devel] Feature Request : dummy paddings for mapping memory holes in privcmd

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.08.13 at 00:18, Guanglin Xu <mzguanglin@xxxxxxxxx> wrote:
> Hi All,
> 
> As a developer of high efficient VMI (Virtual Machine Introspection)
> applications, I appreciate hypervisor to map the whole guest memory
> for us.
> 
> While Xen has been providing mmap_foreign_range() API by libxc and
> privcmd for a long time, it denies to map if the requested page range
> includes memory holes, such as page 160 - 191 legacy video buffer, VGA
> reserved memory, PCI hole, MMIO hole, etc. (see
> http://techfiles.de/dmelanchthon/files/memory_hole.pdf ).
> 
> Maybe you would ask, "what the hell do you want dummy memory holes?!"
> It is because VMI applications are almost about memory searching where
> both the probing of derived separate memory regions and processing on
> them can slow it down a lot.
> 
> In fact, we have recently added such feature for KVM hypervisor.
> However, we are not familiar with Xen. So we hope Xen community can
> help.

So what would you suggest to be mapped in place of those holes?
Right now I think administrative tools are expected to learn about
the guest's physical memory first, and then only attempt to map
the RAM portions of it.

Jan


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