These bindings allow Host <-> VM communication on Hyper-V systems on both Linux and Windows.
Warning: the AF_HYPERV
patches for Linux are not yet merged and hence the
definition of AF_HYPERV
is not yet stable. If other address families are merged
before this one then the value of AF_HYPERV
will change!
Please read the API documentation.
An address on a Hyper-V host consists of two parts:
- a VM GUID
- a well-known service GUID
First generate yourself a service GUID and add this to the registry: this is like opening a hole in a firewall for a TCP port.
New-Item -Path "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Virtualization\GuestCommunicationServices" -Name <Service GUID>
Second discover the GUID of the VM you wish to talk to:
(Get-VM -Name <MY VM NAME>).Id
Third, run a listening server in the VM:
./hvcat -l --echo <Service GUID>
Finally, connect the client on the host to the VM:
./hvcat --vmid <VM GUID> <Service GUID>
Although the connections use the regular SOCKET
APIs, current kernels don't support
calls like select
so we must always use blocking I/O from background threads, rather
than regular asynchronous I/O. This means that the Lwt connection type has been made
opaque.
The client connect
call seems to block forever if the server calls listen
after the client calls connect
. The Lwt_hvsock.connect
works around this
with a self-imposed 1s timeout after which time it will raise ECONNREFUSED
.
For background, see the MSDN article on making an integration service