Dynamic config partitions on boards that support RFID are divided into
a number of segments, each formatted like a partition, with header,
trailer and end tags. The first segment is the current active
configuration.
The segments are initialised by manftest and each contain a different
configuration e.g. firmware variant. The firmware can be instructed
via RFID to copy a segment over the first segment, hence changing the
active configuration. This allows ops to change the configuration of
a board prior to shipment using RFID.
Changes to the dynamic config may need to be written to all segments (in
particular firmware versions written by manftest) or just the first
segment (changes to the active configuration). See SF-111324-SW.
If only the first segment is written the code still needs to be aware of
the possible presence of subsequent segments as writing to a segment may
cause its size to increase, which would overwrite the subsequent
segments and invalidate them.
Boards that do not support RFID will only have one segment in their
dynamic config partition.
Submitted by: Paul Fox <pfox at solarflare.com>
Sponsored by: Solarflare Communications, Inc.
MFC after: 2 days
Differential Revision: https://reviews.freebsd.org/D4302
a1ae428b7d