Re: Sharing variables/memory between host and guest ?

[Avi Kivity <avi@qumranet.com>]

Arn wrote:
> How can one share memory (a few variables not necessarily a page)
> between host/hypervisor and guest VM ?
> Since the guest is just a process within the host, there should be
> existing ways to do this.
> What about using something like debugfs or sysfs, is it possible to
> share variables this way ? Note, I want a system that
> is fast, i.e. changes to shared variable/memory should be visible instantly.
>
> I search the kvm-devel archives and found emails referring to "kshmem"
>  but a search on the kvm-70 code turns up nothing.
> There are also some emails on sharing a page but no final outcome or
> what exactly to do.
>
>   

If you use the -mem-path qemu option, all guest memory will be in a file 
on tmpfs.  You can mmap that file and access all guest memory.  Of 
course, this is hitting the problem with a fairly bit hammer; more 
refined approaches are possible.


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