Time to revisit coolant mapping of M-codes in Linuxcnc

diff --git a/configs/sim/axis/remap/extend-builtins/extend-builtins.ini b/configs/sim/axis/remap/extend-builtins/extend-builtins.ini
index 9f6cee2749..09d3c67ce8 100644
--- a/configs/sim/axis/remap/extend-builtins/extend-builtins.ini
+++ b/configs/sim/axis/remap/extend-builtins/extend-builtins.ini
@@ -68,6 +68,9 @@ REMAP= M0 modalgroup=4 ngc=extend_m0
 REMAP= M1 modalgroup=4 ngc=extend_m1
 REMAP= M60 modalgroup=4 ngc=extend_m60
 
+REMAP = M7  modalgroup=8 argspec=p ngc=extend_m7
+REMAP = M8  modalgroup=8 argspec=p ngc=extend_m8
+REMAP = M9  modalgroup=8 argspec=p ngc=extend_m9
 # this is important - read common_nc_subs/reset_state.ngc
 ON_ABORT_COMMAND= O <reset_state> call
 
diff --git a/src/emc/rs274ngc/interp_convert.cc b/src/emc/rs274ngc/interp_convert.cc
index 4864cc5407..fba0d66d6b 100644
--- a/src/emc/rs274ngc/interp_convert.cc
+++ b/src/emc/rs274ngc/interp_convert.cc
@@ -4068,7 +4068,9 @@ int Interp::convert_m(block_pointer block,       //!< pointer to a block of RS27
       CHP(restore_settings(&_setup, _setup.call_level));
   }
 
-  if (is_user_defined_m_code(block, settings, 8) && ONCE_M(8)) {
+  if (is_user_defined_m_code(block, settings, 8) &&
+      STEP_REMAPPED_IN_BLOCK(block, STEP_M_8) &&
+      ONCE_M(8))  {
      return convert_remapped_code(block, settings, STEP_M_8, 'm',
                    block->m_modes[8]);
   } else if ((block->m_modes[8] == 7) && ONCE_M(8)){
diff --git a/src/emc/rs274ngc/interp_remap.cc b/src/emc/rs274ngc/interp_remap.cc
index 947fac5cfc..3e4069e0e8 100644
--- a/src/emc/rs274ngc/interp_remap.cc
+++ b/src/emc/rs274ngc/interp_remap.cc
@@ -42,6 +42,8 @@ bool Interp::is_m_code_remappable(int m_code)
             m_code == 0 ||
             m_code == 1 ||
             m_code == 6 ||
+            m_code == 7 ||
+            m_code == 8 ||
             m_code == 9 ||
             m_code == 60 ||
             m_code == 61 ||
diff --git a/src/emc/rs274ngc/rs274ngc_pre.cc b/src/emc/rs274ngc/rs274ngc_pre.cc
index 492a72876b..87efe1f718 100644
--- a/src/emc/rs274ngc/rs274ngc_pre.cc
+++ b/src/emc/rs274ngc/rs274ngc_pre.cc
@@ -693,9 +693,18 @@ int Interp::find_remappings(block_pointer block, setup_pointer settings)
     block->remappings.insert(STEP_M_7);
 
     // User defined M-Codes in group 8
-    if (is_user_defined_m_code(block, settings, 8))
-    block->remappings.insert(STEP_M_8);
-
+    if (is_user_defined_m_code(block, settings, 8)) {
+        if (((block->m_modes[8] == 7) && remap_in_progress("M7")) ||
+        ((block->m_modes[8] == 8) && remap_in_progress("M8")) ||
+        ((block->m_modes[8] == 9) && remap_in_progress("M9"))){
+        // recursive behavior
+        CONTROLLING_BLOCK(*settings).builtin_used = true;
+        } else {
+        // non-recursive (ie the built in) behavior
+        block->remappings.insert(STEP_M_8);
+        }
+    }
+    
     // User defined M-Codes in group 9
     if (is_user_defined_m_code(block, settings, 9))
     block->remappings.insert(STEP_M_9);