Until now, block drivers had to deal with a pointer to the client
session component, e.g.: to acknowledge block packets already processed.
When a session was closed, the driver object wasn't informed explicitly,
which leads to defensive programming, or lastly to a race-condition in
test-blk-srv. To prevent from this class of errors, the pointer is now
private to the generic block driver base class, and not accessible to
the concrete driver implementation. Moreover, the driver gets explicitly
informed when a session got invalidated.
Ref #113
* allow to handle a maximum of packets in parallel
that fits free slots in the ack queue
* stop processing packets, when the driver can't handle
more requests in parallel, and resume packet handling,
when the driver is ready again
Instead of using an additional thread in each Session_component of a
block server, which uses the generic block component and driver classes,
replace it with signal dispatchers.
Ref #113
To support components, which implement the block session's server side
rpc object, and which doesn't write data to their device backend immediately,
an additional synchronization call is needed. Thereby, clients like for
instance a file system can tell these components, when a synchronization is
required.
Ref #113
By allocating the packet-stream dataspace for block sessions as
uncached, we can use DMA to directly read and write into the client
buffer. Currently, the OMAP4 SD-card driver is using this feature.
