[review request] zfsboot/zfsloader: support accessing filesystems within a pool

[Ian Lepore]

On Wed, 2012-04-18 at 17:36 +0300, Andriy Gapon wrote:
> on 18/04/2012 17:22 Ian Lepore said the following:
> > YES!  A size field (preferably as the first field in the struct) along
> > with a flag to indicate that it's a new-style boot info struct that
> > starts with a size field, will allow future changes without a lot of
> > drama.  It can allow code that has to deal with the struct without
> > interpretting it (such as trampoline code that has to copy it to a new
> > stack or memory area as part of loading the kernel) to be immune to
> > future changes.
> 
> Yeah, placing the new field at front would immediately break compatibility and
> even access to the flags field :-)
> 

Code would only assume the new field was at the front of the struct if
the new flag is set, otherwise it would use the historical struct
layout.

-- Ian