--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cryptoplugins/cryptospiplugins/test/h4drv/readme.txt	Thu Sep 10 14:01:51 2009 +0300
@@ -0,0 +1,57 @@
+H4 crypto acceleration
+======================
+
+This directory tree contains a "proof of concept" H4 hardware
+acceleration device driver (crypto_h4) and the code required to plug
+it into the preq57 framework (crypto_h4_plugin).
+
+Support
+-------
+
+NOT SUPPORTED!
+
+It is important to note that this plugin/driver is prototype test
+code, and is therefore NOT supported in any way.
+
+In particular it is NOT a reference driver.
+
+
+Limitations
+-----------
+
+Currently the driver has several major limitations:-
+
+1) It is currently slower than the original software implementation...
+
+This is believed to be due to the following issues:
+
+  a) Even using 100% of the H4 CPU power in a tight loop to write/read
+  data to the crypto hardware only runs the driver test case about 30%
+  faster than the old software crypto.
+
+  b) The driver currently fakes DMA transfers for every block (ie. 16
+  bytes).
+
+  Using real DMA, AND setting up longer DMAs may well cause a
+  reduction in CPU loading and increase the throughput of the device
+  driver.
+
+2) Whilst the driver does handle multiple simultaneous user requests,
+including scheduling between them to prevent starvation issues, some
+areas of the device driver are inefficient:-
+
+  a) Both CryptoH4JobRandom and CryptoH4JobAes maintain buffers
+  per-channel, even if that channel has never been used or is stalled.
+
+  Most buffering should be moved to be common to all RNG/AES jobs,
+  with the job objects only saving data needed to later resume a job.
+
+  b) Scheduling for AES jobs is limited to when a job has stalled
+  (ie. either drained all input data or filled the output buffer)
+
+     Theoretically this could allow starvation problems. It is not
+     clear if this is a real issue or not.  It may be better to change
+     the scheduling to only allow rescheduling between device driver
+     requests, rather than within them.
+
+End of notes