doc: add summary table for kernel data passing

Add a table summarizing the key characteristics of each
of the data passing objects.

It is useful for readers to have an overview they can skim without
having to read each section in detail.

Signed-off-by: Marti Bolivar <[email protected]>

Author: mbolivar-nordic

doc/reference/kernel/index.rst

@@ -40,9 +40,34 @@ synchronization.
 Data Passing
 ************
 
-These pages cover kernel services which can be used to pass data between
+These pages cover kernel objects which can be used to pass data between
 threads and ISRs.
 
+The following table summarizes their high-level features.
+
+===============   ==============      ===================    ==============      ==============   =================  ==============  ===============================
+Object            Bidirectional?      Data structure         Data item size      Data Alignment   ISRs can receive?  ISRs can send?  Overrun handling
+===============   ==============      ===================    ==============      ==============   =================  ==============  ===============================
+FIFO              No                  Queue                  Arbitrary [1]              4 B [2]   Yes [3]            Yes             N/A
+LIFO              No                  Queue                  Arbitrary [1]              4 B [2]   Yes [3]            Yes             N/A
+Stack             No                  Array                  Word                          Word   Yes [3]            Yes             Undefined behavior
+Message queue     No                  Ring buffer            Power of two          Power of two   Yes [3]            Yes             Pend thread or return -errno
+Mailbox           Yes                 Queue                  Arbitrary [1]            Arbitrary   No                 No              N/A
+Pipe              No                  Ring buffer [4]        Arbitrary                Arbitrary   No                 No              Pend thread or return -errno
+===============   ==============      ===================    ==============      ==============   =================  ==============  ===============================
+
+[1] Callers allocate space for queue overhead in the data
+elements themselves.
+
+[2] Objects added with k_fifo_alloc_put() and k_lifo_alloc_put()
+do not have alignment constraints, but use temporary memory from the
+calling thread's resource pool.
+
+[3] ISRs can receive only when passing K_NO_WAIT as the timeout
+argument.
+
+[4] Optional.
+
 .. toctree::
    :maxdepth: 2