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

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


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