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+Profiling the Cryptech Alpha
+============================
+
+Origin
+------
+
+This code was copied from https://github.com/ErichStyger/mcuoneclipse.git,
+directory `Examples/KDS/FRDM-K64F120M/FRDM-K64F_Profiling/Profiling`, commit
+9b7eedddd8b24968128582aedc63be95b61f782c, dated Mon Jan 9 16:56:17 2017 +0100.
+
+References
+----------
+
+I recommend reading both of these to understand how the profiling code works.
+
+1. [Tutorial: Using GNU Profiling (gprof) with ARM Cortex-M](https://mcuoneclipse.com/2015/08/23/tutorial-using-gnu-profiling-gprof-with-arm-cortex-m/)
+
+2. [Semihosting with ARM, GCC, and OpenOCD](http://bgamari.github.io/posts/2014-10-31-semihosting.html)
+
+How to build
+------------
+
+From the top level, run
+
+    $ make DO_PROFILING=1 hsm
+
+By default, all code is profiled, *except* the profiling code itself,
+because that would cause fatal recursion.
+
+How to run
+----------
+
+You need to start OpenOCD on the host, and enable semihosting, at least
+before you try to use it as a remote file system.
+
+I recommend executing the following in the `projects/hsm` directory, so that
+`gmon.out` ends up in the same directory as `hsm.elf`.
+
+Start the debugger:
+
+    $ ../../bin/debug hsm
+
+In another window, connect to OpenOCD:
+
+    $ telnet localhost 4444
+
+In the OpenOCD console, enable semihosting:
+
+    > arm semihosting enable
+    > exit
+
+Then connect to the Cryptech management console:
+
+    $ cryptech_console
+
+In the Cryptech console, type `profile start`, then start the unit test or
+whatever will be exercising the hsm. Afterwards, in the console, type
+`profile stop`.
+
+After invoking `profile stop`, it can take several minutes to write
+`gmon.out` over OpenOCD to the host.
+
+In the `projects/hsm` directory, run `gprof` to analyse the `gmon.out` file:
+
+    $ gprof hsm.elf >gprof.txt