Hi Andrew,

 > But we'll still need a memcpy, unless we use a separate io vector when
> sending the message to the kdbus FD, but I'd have to check if it
> doesn't break the splitting rules.
>

So one thought here would be to add extra space in the beginning of the 
body used by gvariant builder.  That way we can fill it with the variant 
contents when we finalize the builder.  We might need to keep an extra 
book-keeping variable, something like body_offset, to know where the 
body actually begins.  It will be always 0 for dbus-1.

Perhaps you can think of something better.

Regards,
-Denis