On 15.09.2016 09:12, Ivo Smits wrote:

VirtualBox has Guest Properties, which I think are very similar to VMware's GuestVariables. You can use Guest Properties via the command line: https://forums.virtualbox.org/viewtopic.php?t=10823

Or via the COM API: https://www.virtualbox.org/sdkref/interface_i_machine.html#a9f2fffade4b897eb659cc4602694676d

Right, Guest Properties sounds like a suitable mechanism. It has reasonably high limits (can easily handle several 100KB), and handles anything which is valid UTF-8. Don't try to abuse it as a way to pass binary data directly, because then you'll run into 'random' failures when the UTF-8 validation sets off the alarm. Oh, and if you pass large data it's probably a good idea to mark the guest property as transient so that it doesn't cause VM settings bloat.

On the guest side you'll probably need the VirtualBox Guest Additions including its kernel module to be able to access the properties.

Not "probably", Guest Additions in the VM are a must have if you're intending to use Guest Properties.




Op 15-9-2016 om 4:19 schreef Alex Crawford:
I've been kicking around the idea of adding another request type to
VMMDev that exposes an opaque chunk of data provided by the user. This
is intended to allow users to pass configuration data to guests which
support reading from this interface.

At CoreOS, we are working on a project called Ignition [1], which
handles machine provisioning tasks (setting up filesystems, creating
users, enabling services, etc.). In order to support VirtualBox, we need
a way for users to pass their Ignition config to the CoreOS Linux guest
(ideally via the hypervisor). We do this via GuestVariables on VMware
and the firmware configuration device on QEMU. I couldn't find anything
in VirtualBox which would allow us similar functionality.

I'd like to add an extra request handler to expose just this piece of
information. I had considered making a much more general mechanism,
similar to GuestVariables, but I'd prefer to keep things simple and get
the developers' feedback before I started work. What do you all think?


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