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Re: [libvirt] Memory access API

On Wed, Jun 19, 2013 at 04:29:48AM +0200, Marek Marczykowski-Górecki wrote:
> Hi,
> Is there any zero-copy VM memory access API in libvirt? I see only
> virDomainMemoryPeek function, which copy some memory from VM and do not permit
> VM memory modifications.
> What I'm looking for is xen xc_map_foreign_pages or
> xc_gnttab_map_domain_grant_refs equivalent/wrapper. IOW map memory pages to
> dom0 address space, without copy. I know that not every hypervisor supports
> it, but it is useful to build a high-performance communication channel on top
> of it.

The only way to access memory from libvirt is via virDomainMemoryPeek

QEMU has an 'ivshm' device for doing shared memory segments between
VMs and/or host, which would be zero-copy but support for this has
not yet been integrated in libvirt. Patches are welcome if anyone
wants to add this though.

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