diff --git a/arch/sim/src/Makefile b/arch/sim/src/Makefile
index 02b76288b7c2b..b7f5196a57c6a 100644
--- a/arch/sim/src/Makefile
+++ b/arch/sim/src/Makefile
@@ -195,15 +195,8 @@ endif
 
 # Override in Make.defs if linker is not 'ld'
 
-ifeq ($(HOSTOS),Darwin)
-  LDSTARTGROUP ?=
-  LDENDGROUP ?=
-  LDUNEXPORTSYMBOLS ?= -unexported_symbols_list $(HOSTOS)-names.dat
-else
-  LDSTARTGROUP ?= --start-group
-  LDENDGROUP ?= --end-group
-  LDUNEXPORTSYMBOLS ?=
-endif
+LDSTARTGROUP ?= --start-group
+LDENDGROUP ?= --end-group
 
 EXTRA_LIBS ?=
 EXTRA_LIBPATHS ?=
@@ -299,15 +292,10 @@ else
 	$(Q) cp nuttx-names.dat $@
 endif
 
-Darwin-names.dat: nuttx-names.dat
-	$(Q) cat $^ | sed -e "s/^\([^[:space:]][^[:space:]]*\)[[:space:]].*/_\1/g" >$@
-
 nuttx.rel : libarch$(LIBEXT) board/libboard$(LIBEXT) $(HOSTOS)-names.dat $(LINKOBJS)
 	$(Q) echo "LD:  nuttx.rel"
-	$(Q) $(LD) -r $(LDLINKFLAGS) $(RELPATHS) $(EXTRA_LIBPATHS) -o $@ $(REQUIREDOBJS) $(LDSTARTGROUP) $(RELLIBS) $(EXTRA_LIBS) $(LDENDGROUP) $(LDUNEXPORTSYMBOLS)
-ifneq ($(HOSTOS),Darwin)
+	$(Q) $(LD) -r $(LDLINKFLAGS) $(RELPATHS) $(EXTRA_LIBPATHS) -o $@ $(REQUIREDOBJS) $(LDSTARTGROUP) $(RELLIBS) $(EXTRA_LIBS) $(LDENDGROUP)
 	$(Q) $(OBJCOPY) --redefine-syms=$(HOSTOS)-names.dat $@
-endif
 
 # Generate the final NuttX binary by linking the host-specific objects with the NuttX
 # specific objects (with munged names)
@@ -318,6 +306,7 @@ nuttx$(EXEEXT): cleanrel nuttx.rel $(HOSTOBJS)
 	$(Q) $(NM) $(TOPDIR)/$@ | \
 		grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
 		sort > $(TOPDIR)/System.map
+	$(Q) rm -f nuttx.rel
 
 # This is part of the top-level export target
 
@@ -338,7 +327,7 @@ export_startup: board/libboard$(LIBEXT) up_head.o $(HOSTOBJS)
 depend: .depend
 
 cleanrel:
-	$(Q) rm -f nuttx.rel $(HOSTOS)-names.dat
+	$(Q) rm -f nuttx.rel GNU/Linux-names.dat Cygwin-names.dat
 
 clean: cleanrel
 	$(Q) if [ -e board/Makefile ]; then \
diff --git a/arch/sim/src/sim/up_initialstate.c b/arch/sim/src/sim/up_initialstate.c
index 129d3be8ee43e..3ddb1128d7947 100644
--- a/arch/sim/src/sim/up_initialstate.c
+++ b/arch/sim/src/sim/up_initialstate.c
@@ -67,6 +67,6 @@
 void up_initial_state(struct tcb_s *tcb)
 {
   memset(&tcb->xcp, 0, sizeof(struct xcptcontext));
-  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->adj_stack_ptr - sizeof(xcpt_reg_t);
+  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->adj_stack_ptr;
   tcb->xcp.regs[JB_PC] = (xcpt_reg_t)tcb->start;
 }
diff --git a/arch/sim/src/sim/up_setjmp32.S b/arch/sim/src/sim/up_setjmp32.S
index 13b202e63c76d..15880cbf7393c 100644
--- a/arch/sim/src/sim/up_setjmp32.S
+++ b/arch/sim/src/sim/up_setjmp32.S
@@ -46,12 +46,8 @@
 #ifdef __CYGWIN__
 # define SYMBOL(s) _##s
 #else
-#ifdef __ELF__
-# define SYMBOL(s) _##s
-#else
 # define SYMBOL(s) s
 #endif
-#endif
 
 /**************************************************************************
  * Public Functions
@@ -59,7 +55,7 @@
 
 	.text
 	.globl	SYMBOL(up_setjmp)
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.type	SYMBOL(up_setjmp), @function
 #endif
 SYMBOL(up_setjmp):
@@ -90,11 +86,11 @@ SYMBOL(up_setjmp):
 
 	xorl	%eax, %eax
 	ret
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.size	SYMBOL(up_setjmp), . - SYMBOL(up_setjmp)
 #endif
 	.globl	SYMBOL(up_longjmp)
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.type	SYMBOL(up_longjmp), @function
 #endif
 SYMBOL(up_longjmp):
@@ -116,7 +112,7 @@ SYMBOL(up_longjmp):
 	/* Jump to saved PC.  */
 
 	jmp		*%edx
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.size SYMBOL(up_longjmp), . - SYMBOL(up_longjmp)
 #endif
 
diff --git a/arch/sim/src/sim/up_setjmp64.S b/arch/sim/src/sim/up_setjmp64.S
index 0e1063ba63760..92cc866523603 100644
--- a/arch/sim/src/sim/up_setjmp64.S
+++ b/arch/sim/src/sim/up_setjmp64.S
@@ -81,11 +81,7 @@
 //# define SYMBOL(s) _##s
 # define SYMBOL(s) s
 #else
-#ifdef __ELF__
 # define SYMBOL(s) s
-#else
-# define SYMBOL(s) _##s
-#endif
 #endif
 
 /**************************************************************************
@@ -95,7 +91,7 @@
 	.text
 	.align	4
 	.globl	SYMBOL(up_setjmp)
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.type	SYMBOL(up_setjmp), @function
 #endif
 SYMBOL(up_setjmp):
@@ -132,13 +128,13 @@ SYMBOL(up_setjmp):
 
 	ret
 
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.size	SYMBOL(up_setjmp), . - SYMBOL(up_setjmp)
 #endif
 
 	.align	4
 	.globl	SYMBOL(up_longjmp)
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.type	SYMBOL(up_longjmp), @function
 #endif
 SYMBOL(up_longjmp):
@@ -161,7 +157,7 @@ SYMBOL(up_longjmp):
 
 	jmp		*JB_RSI(REGS)	/* Save 8: rsi */
 
-#ifdef __ELF__
+#ifndef __CYGWIN__
 	.size SYMBOL(up_longjmp), . - SYMBOL(up_longjmp)
 #endif
 
diff --git a/arch/sim/src/sim/up_stackframe.c b/arch/sim/src/sim/up_stackframe.c
index 887de5c70347a..eecb3668af412 100644
--- a/arch/sim/src/sim/up_stackframe.c
+++ b/arch/sim/src/sim/up_stackframe.c
@@ -124,7 +124,7 @@ FAR void *up_stack_frame(FAR struct tcb_s *tcb, size_t frame_size)
 
   /* Reset the initial state */
 
-  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->adj_stack_ptr - sizeof(xcpt_reg_t);
+  tcb->xcp.regs[JB_SP] = (xcpt_reg_t)tcb->adj_stack_ptr;
 
   /* And return a pointer to the allocated memory */
 
diff --git a/binfmt/binfmt_globals.c b/binfmt/binfmt_globals.c
index 94f98f13d49b4..ea01ab025b257 100644
--- a/binfmt/binfmt_globals.c
+++ b/binfmt/binfmt_globals.c
@@ -56,7 +56,7 @@
  * protection to simply disable pre-emption when accessing this list.
  */
 
-FAR struct binfmt_s *g_binfmts = NULL;
+FAR struct binfmt_s *g_binfmts;
 
 /****************************************************************************
  * Private Functions
diff --git a/boards/sim/sim/sim/README.txt b/boards/sim/sim/sim/README.txt
index 18a352e869ade..31091845a8658 100644
--- a/boards/sim/sim/sim/README.txt
+++ b/boards/sim/sim/sim/README.txt
@@ -153,12 +153,12 @@ The simulation build is a two pass build:
     created called nuttx.rel.  This includes all of the files that are part
     of the NuttX "domain."
 
-  2. On the second pass, the files which are in the host OS domain are build
+  2. On the second pass, the files are are in the host OS domain are build
      and then linked with nuttx.rel to generate the simulation program.
 
 NuttX is a POSIX compliant RTOS and is normally build on a POSIX compliant
 host environment (like Linux or Cygwin).  As a result, the same symbols are
-exported by both the NuttX domain and the host domain.  How can we keep them
+exported by both the NuttX doman and the host domain.  How can we keep them
 separate?
 
 This is done using the special file nuttx-name.dat.  This file just contains
@@ -181,10 +181,6 @@ which version of strlen() you call.  Other times, it can cause subtle,
 mysterious errors.  Usually, however, callng the wrong function in the wrong
 OS results in a fatal crash.
 
-On macOS, instead of objcopy, -unexported_symbols_list linker option is
-used to hide symbols in the NuttX domain, using the same list of symbols
-from nuttx-name.dat.
-
 Networking Issues
 -----------------
 I never did get networking to work on the sim target.  It tries to use the
@@ -491,17 +487,6 @@ Common Configuration Information
         CONFIG_SIM_X8664_SYSTEMV=n
         CONFIG_SIM_M32=n
 
-     g. macOS, 64-bit, 64-bit build
-
-        CONFIG_HOST_LINUX=n
-        CONFIG_HOST_MACOS=y
-        CONFIG_HOST_WINDOWS=n
-        CONFIG_HOST_X86=n
-        CONFIG_HOST_X86_64=y
-        CONFIG_SIM_X8664_MICROSOFT=n
-        CONFIG_SIM_X8664_SYSTEMV=y
-        CONFIG_SIM_M32=n
-
 Configuration Sub-Directories
 -----------------------------
 
diff --git a/boards/sim/sim/sim/configs/cxxtest/Make.defs b/boards/sim/sim/sim/configs/cxxtest/Make.defs
index 53fe2d56dc41e..7146e1ad7128d 100644
--- a/boards/sim/sim/sim/configs/cxxtest/Make.defs
+++ b/boards/sim/sim/sim/configs/cxxtest/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
@@ -116,7 +116,9 @@ EXTRA_LIBPATHS = -L "${shell dirname "$(LIBSUPXX)"}"
 EXTRA_LIBS = -lsupc++
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
+  LDLINKFLAGS += -g
   CCLINKFLAGS += -g
+  LDFLAGS += -g
 endif
 
 ifeq ($(CONFIG_SIM_M32),y)
diff --git a/boards/sim/sim/sim/configs/nsh2/Make.defs b/boards/sim/sim/sim/configs/nsh2/Make.defs
index b00ada0bfbca9..e329be3f6d141 100644
--- a/boards/sim/sim/sim/configs/nsh2/Make.defs
+++ b/boards/sim/sim/sim/configs/nsh2/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
+HOSTOS			= ${shell uname -o 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION	= -g
@@ -108,7 +108,9 @@ CCLINKFLAGS		= $(ARCHSCRIPT)	# Link flags used with $(CC)
 LDFLAGS			= $(ARCHSCRIPT)	# For backward compatibility, same as CCLINKFLAGS
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
+  LDLINKFLAGS		+= -g
   CCLINKFLAGS		+= -g
+  LDFLAGS			+= -g
 endif
 
 ifeq ($(CONFIG_SIM_M32),y)
diff --git a/boards/sim/sim/sim/scripts/Make.defs b/boards/sim/sim/sim/scripts/Make.defs
index 9eb3d13c2eaa7..94d53bb87263e 100644
--- a/boards/sim/sim/sim/scripts/Make.defs
+++ b/boards/sim/sim/sim/scripts/Make.defs
@@ -37,7 +37,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_WINDOWS_MSYS),y)
   DIRLINK = $(TOPDIR)/tools/copydir.sh
@@ -115,7 +115,9 @@ CCLINKFLAGS = $(ARCHSCRIPT) # Link flags used with $(CC)
 LDFLAGS = $(ARCHSCRIPT) # For backward compatibility, same as CCLINKFLAGS
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
+  LDLINKFLAGS += -g
   CCLINKFLAGS += -g
+  LDFLAGS += -g
 endif
 
 ifeq ($(CONFIG_SIM_M32),y)
diff --git a/boards/sim/sim/sim/src/Makefile b/boards/sim/sim/sim/src/Makefile
index 7f4bbfa517849..0b01b424b474b 100644
--- a/boards/sim/sim/sim/src/Makefile
+++ b/boards/sim/sim/sim/src/Makefile
@@ -35,10 +35,8 @@
 
 include $(TOPDIR)/Make.defs
 
-# Add dummy.c to ensure that we have at least one object.
-# On some platforms like macOS, we can't create an empty archive.
 ASRCS =
-CSRCS = dummy.c
+CSRCS =
 
 ifeq ($(CONFIG_BOARD_LATE_INITIALIZE),y)
   CSRCS += sim_boot.c
diff --git a/boards/sim/sim/sim/src/dummy.c b/boards/sim/sim/sim/src/dummy.c
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/boards/x86/qemu/qemu-i486/scripts/Make.defs b/boards/x86/qemu/qemu-i486/scripts/Make.defs
index df4c8799b7f7b..e153be8967eec 100644
--- a/boards/x86/qemu/qemu-i486/scripts/Make.defs
+++ b/boards/x86/qemu/qemu-i486/scripts/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
diff --git a/mm/umm_heap/umm_globals.c b/mm/umm_heap/umm_globals.c
index a00ce3c4ec672..012aac76315d9 100644
--- a/mm/umm_heap/umm_globals.c
+++ b/mm/umm_heap/umm_globals.c
@@ -64,5 +64,5 @@
 #else
 /* Otherwise, the user heap data structures are in common .bss */
 
-struct mm_heap_s g_mmheap = {};
+struct mm_heap_s g_mmheap;
 #endif
diff --git a/tools/Makefile.host b/tools/Makefile.host
index 71e87e59c6d56..07ebe9ea3b52e 100644
--- a/tools/Makefile.host
+++ b/tools/Makefile.host
@@ -43,7 +43,7 @@ include ${TOPDIR}/tools/Config.mk
 # Define HOSTCC on the make command line if it differs from these defaults
 # Define HOSTCFLAGS with -g on the make command line to build debug versions
 
-HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o || echo "Other"}
 
 ifeq ($(HOSTOS),MinGW)
 
diff --git a/tools/sethost.sh b/tools/sethost.sh
index 2983095dd893f..2cd63ff0647bd 100755
--- a/tools/sethost.sh
+++ b/tools/sethost.sh
@@ -244,9 +244,9 @@ echo "  Refreshing..."
 cd $nuttx || { echo "ERROR: failed to cd to $nuttx"; exit 1; }
 make clean_context 1>/dev/null 2>&1
 if [ "X${debug}" = "Xy" ]; then
-  make olddefconfig V=1 || { echo "ERROR: failed to refresh"; exit 1; }
+  make olddefconfig V=1
 else
-  make olddefconfig 1>/dev/null || { echo "ERROR: failed to refresh"; exit 1; }
+  make olddefconfig 1>/dev/null 2>&1
 fi
 
 # Move config file to correct location and restore any previous .config