On 23/08/2013 23:57, Peter Grehan wrote:
>> I always wondered about virtualization environments which have pageable
>> guest memory - how does the guest kernel handle situations where it
>> really needs non-pageable memory? Does is simply "not care" because for
>> it the memory access looks just like it isn't paged but is simply very,
>> very slow?
>  Yes - from the guest's point of view, what it thinks is physical memory
> appears wired.
>> What about time-sensitive situations (like the originally
>> mentioned PCI-passthrough)?
>  PCI passthru is a special case since the h/w requires that the target
> of a DMA transfer is present - there is currently no way for the IOMMU
> to generate the equivalent of page faults. So, for PCI passthru, all of
> guest memory has to be wired host memory.
>  For time-sensitive situations, there's not a lot of options other than
> forcing guest memory to be wired, since there isn't visibility into the
> host without having o/s-specific "tools" that could communicate this
> information to the hypervisor.

Ok, that is how I understood it also, but I thought that maybe there was
some way of telling which guest memory belongs to the kernel and only
wire those pages.

Attachment: signature.asc
Description: OpenPGP digital signature

Reply via email to