[vbox-dev] Using HGCM

[Nev]

Hi Michael,

Not meaning to be pushy but my day is just ending, and I suspect yours is just beginning,
and you have not even seen the previous email.
I have made some progress on searching the source for answers to my own questions.
Hence this email.

I have found "Host Guest Shared Memory Interface" or HGSMI. Which has a number of functions such as:
HGSMICreate, HGSMIDestroy, HGSMIHostRead, HGSMIGuestRead.
These look like they maybe close to the functions that I need, but are LOCAL HIDDEN symbols in VBoxDD.so

But all the functions they call are public symbols in VBoxRT, VBoxVMM and VBoxREM.

My Question is do these function create memory that is shared between Host and Guest 
and can the memory be read and written without generating exception on every read or write?

Is this memory accessible from Ring 3?

Do I need to implement this interface as Device or Driver, or would a shared library do the job?

If a device is required, is VBoxSampleDevice.cpp a good starting point ?

If Driver is required is there a good starting point ?

Sorry if these question are too simplistic, but I trying to not waste time by following a wrong path.

PS. should I change the subject of email ?

Thanks
Nev