diff --git a/boards/z80/z180/p112/README.txt b/boards/z80/z180/p112/README.txt
index 7a32cc6a90..3bdb5961e6 100644
--- a/boards/z80/z180/p112/README.txt
+++ b/boards/z80/z180/p112/README.txt
@@ -138,6 +138,14 @@ the Z85230 ESCC channel A.
 Status
 ======
 
+2020-4-11:  Support for CONFIG_CAN_PASS_STRUCTS was removed in NuttX-9.1.
+  This was necessary to enforce some POSIX interface compliance but also
+  means that ALL older SDCC versions will no long build with NuttX.  I have
+  been told that the newest SDCC compilers can indeed pass structure and
+  union parameters and return values.  If that is correct, then perhaps
+  the newer SDCC compilers will be used.  Otherwise, it will be necessary
+  to use some other, more compliant compiler.
+
 2014-8-22:  After some time idling away, I tried rebuilding with Windows 8,
   the latest MinGW and the latest SDCC.  I fixed a few things but there a
   still a few issues.  The last "show stopper" before I gave up for now was
diff --git a/boards/z80/z80/z80sim/README.txt b/boards/z80/z80/z80sim/README.txt
index c2a47d0fe5..9a6610d0a8 100644
--- a/boards/z80/z80/z80sim/README.txt
+++ b/boards/z80/z80/z80sim/README.txt
@@ -6,6 +6,7 @@ This port uses an instruction set simulator called z80sim.
 
 The SDCC toolchain is available from http://sdcc.sourceforge.net/.  All
 testing has been performed using version 2.6.0 of the SDCC toolchain.
+IMPORTANT: See notes in the SDCC section.
 
 Contents
 ^^^^^^^^
@@ -138,6 +139,14 @@ or custom built for Cygwin (see below).
 SDCC
 ^^^^
 
+IMPORTANT NOTE as of 2020-4-11:  Support for CONFIG_CAN_PASS_STRUCTS was
+removed in NuttX-9.1.  This was necessary to enforce some POSIX interface
+compliance but also means that ALL older SDCC versions will no long build
+with NuttX.  I have been told that the newest SDCC compilers can indeed
+pass structure and union parameters and return values.  If that is correct,
+then perhaps the newer SDCC compilers will be used.  Otherwise, it will be
+necessary to use some other, more compliant compiler.
+
 These z80 configurations all use the SDCC toolchain (http://sdcc.sourceforge.net/).
 Source and pre-built SDCC binaries can be downloaded from the SDCC SourceForge
 site: http://sourceforge.net/projects/sdcc/files/ .  Pre-built binaries are