Taking in a filehandle gives the user quite a bit more freedom on how to
handle boot log output. They can set up a kqueue watch on it and
redirect output somewhere else etc etc. The implementation for this has
us take in a new BootLog type that has two options:
1. .file, which is analogous to what we had prior. Just provide a URL
and a true by default append field.
2. .fileHandle which is the new addition. Can pass any fd that is
writable, and the VMM should write serial console output to it.
Today this protocols create method is just odd. Our only implementation
of it immediately casts to LinuxContainer, failing if it cannot do so. I
think what might make more sense is to pass in a configuration itself
with core parameters that we expect every vmm to be able to support, and
then in a specific implementation they can continue to cast this type to
a specific one to possibly extract some extra configuration values
(rosetta for VZ for example).
This rework will also make it simpler to support a Pod type, as the vm
setup is identical and simple.
Kathryn Baldauf