* Introduce feature flags which allows the proxy and m1n1 to determine which
features they have in common.
* Add a feature flag that disables checksumming (by replacing checksums with
constant values) for the data packets exchanged by REQ_MEMREAD, REQ_MEMWRITE
and REQ_EVENT. The feature is enabled if m1n1 supports it; checksumming is kept
enabled for UART communication.
* To ensure no packet loss when checksumming is disabled, an extra sentinel
value is added after the exchanged data for memory read/write operations.
Signed-off-by: Vincent Duvert <vincent@duvert.net>
This allows the proxy to call back to Python for handling exceptions or
other events, passing reason information about why it was invoked and
returning normally when the exception has been handled.
Signed-off-by: Hector Martin <marcan@marcan.st>
