🚸 Use Z_STEPPER_ALIGN_STEPPER_XY to enable

Marlin/Configuration_adv.h

     //#define Z_STEPPERS_ORIENTATION 0
   #endif
 
-  // Provide Z stepper positions for more rapid convergence in bed alignment.
-  // Requires triple stepper drivers (i.e., set NUM_Z_STEPPER_DRIVERS to 3)
-  //#define Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS
-  #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
-    // Define Stepper XY positions for Z1, Z2, Z3 corresponding to
-    // the Z screw positions in the bed carriage.
-    // Define one position per Z stepper in stepper driver order.
-    #define Z_STEPPER_ALIGN_STEPPER_XY { { 210.7, 102.5 }, { 152.6, 220.0 }, { 94.5, 102.5 } }
-  #else
+  /**
+   * Z Stepper positions for more rapid convergence in bed alignment.
+   * Requires NUM_Z_STEPPER_DRIVERS to be 3 or 4.
+   *
+   * Define Stepper XY positions for Z1, Z2, Z3... corresponding to the screw
+   * positions in the bed carriage, with one position per Z stepper in stepper
+   * driver order.
+   */
+  //#define Z_STEPPER_ALIGN_STEPPER_XY { { 210.7, 102.5 }, { 152.6, 220.0 }, { 94.5, 102.5 } }
+
+  #ifndef Z_STEPPER_ALIGN_STEPPER_XY
     // Amplification factor. Used to scale the correction step up or down in case
     // the stepper (spindle) position is farther out than the test point.
     #define Z_STEPPER_ALIGN_AMP 1.0       // Use a value > 1.0 NOTE: This may cause instability!

Marlin/src/feature/z_stepper_align.cpp

 
 xy_pos_t ZStepperAlign::xy[NUM_Z_STEPPER_DRIVERS];
 
-#if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+#if HAS_Z_STEPPER_ALIGN_STEPPER_XY
   xy_pos_t ZStepperAlign::stepper_xy[NUM_Z_STEPPER_DRIVERS];
 #endif
 
 
   COPY(xy, xy_init);
 
-  #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+  #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
     constexpr xy_pos_t stepper_xy_init[] = Z_STEPPER_ALIGN_STEPPER_XY;
     static_assert(
       COUNT(stepper_xy_init) == NUM_Z_STEPPER_DRIVERS,

Marlin/src/feature/z_stepper_align.h

   public:
     static xy_pos_t xy[NUM_Z_STEPPER_DRIVERS];
 
-    #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+    #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
       static xy_pos_t stepper_xy[NUM_Z_STEPPER_DRIVERS];
     #endif
 

Marlin/src/gcode/calibrate/G34_M422.cpp

   #include "../../module/tool_change.h"
 #endif
 
-#if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+#if HAS_Z_STEPPER_ALIGN_STEPPER_XY
   #include "../../libs/least_squares_fit.h"
 #endif
 
         break;
       }
 
-      const float z_auto_align_amplification = TERN(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS, Z_STEPPER_ALIGN_AMP, parser.floatval('A', Z_STEPPER_ALIGN_AMP));
+      const float z_auto_align_amplification = TERN(HAS_Z_STEPPER_ALIGN_STEPPER_XY, Z_STEPPER_ALIGN_AMP, parser.floatval('A', Z_STEPPER_ALIGN_AMP));
       if (!WITHIN(ABS(z_auto_align_amplification), 0.5f, 2.0f)) {
         SERIAL_ECHOLNPGM("?(A)mplification out of bounds (0.5-2.0).");
         break;
       // Now, the Z origin lies below the build plate. That allows to probe deeper, before run_z_probe throws an error.
       // This hack is un-done at the end of G34 - either by re-homing, or by using the probed heights of the last iteration.
 
-      #if DISABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+      #if !HAS_Z_STEPPER_ALIGN_STEPPER_XY
         float last_z_align_move[NUM_Z_STEPPER_DRIVERS] = ARRAY_N_1(NUM_Z_STEPPER_DRIVERS, 10000.0f);
       #else
         float last_z_align_level_indicator = 10000.0f;
             z_maxdiff = 0.0f,
             amplification = z_auto_align_amplification;
 
-      #if DISABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+      #if !HAS_Z_STEPPER_ALIGN_STEPPER_XY
         bool adjustment_reverse = false;
       #endif
 
         z_maxdiff = z_measured_max - z_measured_min;
         z_probe = Z_BASIC_CLEARANCE + z_measured_max + z_maxdiff;
 
-        #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+        #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
           // Replace the initial values in z_measured with calculated heights at
           // each stepper position. This allows the adjustment algorithm to be
           // shared between both possible probing mechanisms.
           return false;
         };
 
-        #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+        #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
           // Check if the applied corrections go in the correct direction.
           // Calculate the sum of the absolute deviations from the mean of the probe measurements.
           // Compare to the last iteration to ensure it's getting better.
           float z_align_move = z_measured[zstepper] - z_measured_min;
           const float z_align_abs = ABS(z_align_move);
 
-          #if DISABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+          #if !HAS_Z_STEPPER_ALIGN_STEPPER_XY
             // Optimize one iteration's correction based on the first measurements
             if (z_align_abs) amplification = (iteration == 1) ? _MIN(last_z_align_move[zstepper] / z_align_abs, 2.0f) : z_auto_align_amplification;
 
           // Lock all steppers except one
           stepper.set_all_z_lock(true, zstepper);
 
-          #if DISABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+          #if !HAS_Z_STEPPER_ALIGN_STEPPER_XY
             // Decreasing accuracy was detected so move was inverted.
             // Will match reversed Z steppers on dual steppers. Triple will need more work to map.
             if (adjustment_reverse) {
  *
  *   S<index> : Index of the probe point to set
  *
- * With Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS:
+ * With Z_STEPPER_ALIGN_STEPPER_XY:
  *   W<index> : Index of the Z stepper position to set
  *              The W and S parameters may not be combined.
  *
 
   const bool is_probe_point = parser.seen('S');
 
-  if (TERN0(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS, is_probe_point && parser.seen('W'))) {
+  if (TERN0(HAS_Z_STEPPER_ALIGN_STEPPER_XY, is_probe_point && parser.seen('W'))) {
     SERIAL_ECHOLNPGM("?(S) and (W) may not be combined.");
     return;
   }
 
   xy_pos_t *pos_dest = (
-    TERN_(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS, !is_probe_point ? z_stepper_align.stepper_xy :)
+    TERN_(HAS_Z_STEPPER_ALIGN_STEPPER_XY, !is_probe_point ? z_stepper_align.stepper_xy :)
     z_stepper_align.xy
   );
 
-  if (!is_probe_point && TERN1(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS, !parser.seen('W'))) {
-    SERIAL_ECHOLNPGM("?(S)" TERN_(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS, " or (W)") " is required.");
+  if (!is_probe_point && TERN1(HAS_Z_STEPPER_ALIGN_STEPPER_XY, !parser.seen('W'))) {
+    SERIAL_ECHOLNPGM("?(S)" TERN_(HAS_Z_STEPPER_ALIGN_STEPPER_XY, " or (W)") " is required.");
     return;
   }
 
     }
   }
   else {
-    #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+    #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
       position_index = parser.intval('W') - 1;
       if (!WITHIN(position_index, 0, NUM_Z_STEPPER_DRIVERS - 1)) {
         SERIAL_ECHOLNPGM("?(W) Z-stepper index invalid.");
       SP_Y_STR, z_stepper_align.xy[i].y
     );
   }
-  #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+  #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
     LOOP_L_N(i, NUM_Z_STEPPER_DRIVERS) {
       report_echo_start(forReplay);
       SERIAL_ECHOLNPGM_P(

Marlin/src/inc/Conditionals_adv.h

 #endif
 
 #if ENABLED(Z_STEPPER_AUTO_ALIGN)
-  #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+  #ifdef Z_STEPPER_ALIGN_STEPPER_XY
+    #define HAS_Z_STEPPER_ALIGN_STEPPER_XY 1
     #undef Z_STEPPER_ALIGN_AMP
   #endif
   #ifndef Z_STEPPER_ALIGN_AMP
 #endif
 
 // Flag whether least_squares_fit.cpp is used
-#if ANY(AUTO_BED_LEVELING_UBL, AUTO_BED_LEVELING_LINEAR, Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+#if ANY(AUTO_BED_LEVELING_UBL, AUTO_BED_LEVELING_LINEAR, HAS_Z_STEPPER_ALIGN_STEPPER_XY)
   #define NEED_LSF 1
 #endif
 

Marlin/src/inc/SanityCheck.h

   #error "NOZZLE_PARK_X_ONLY is now NOZZLE_PARK_MOVE 1."
 #elif defined(NOZZLE_PARK_Y_ONLY)
   #error "NOZZLE_PARK_X_ONLY is now NOZZLE_PARK_MOVE 2."
+#elif defined(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+  #error "Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS is now just Z_STEPPER_ALIGN_STEPPER_XY."
 #endif
 
 constexpr float arm[] = AXIS_RELATIVE_MODES;
     #error "Z_STEPPER_AUTO_ALIGN requires NUM_Z_STEPPER_DRIVERS greater than 1."
   #elif !HAS_BED_PROBE
     #error "Z_STEPPER_AUTO_ALIGN requires a Z-bed probe."
-  #elif ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+  #elif HAS_Z_STEPPER_ALIGN_STEPPER_XY
     static_assert(WITHIN(Z_STEPPER_ALIGN_AMP, 0.5, 2.0), "Z_STEPPER_ALIGN_AMP must be between 0.5 and 2.0.");
     #if NUM_Z_STEPPER_DRIVERS < 3
-      #error "Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS requires NUM_Z_STEPPER_DRIVERS to be 3 or 4."
+      #error "Z_STEPPER_ALIGN_STEPPER_XY requires NUM_Z_STEPPER_DRIVERS to be 3 or 4."
     #endif
   #endif
 #endif

Marlin/src/module/settings.cpp

   #endif
 
   //
-  // Z_STEPPER_AUTO_ALIGN, Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS
+  // Z_STEPPER_AUTO_ALIGN, HAS_Z_STEPPER_ALIGN_STEPPER_XY
   //
   #if ENABLED(Z_STEPPER_AUTO_ALIGN)
     xy_pos_t z_stepper_align_xy[NUM_Z_STEPPER_DRIVERS];             // M422 S X Y
-    #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+    #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
       xy_pos_t z_stepper_align_stepper_xy[NUM_Z_STEPPER_DRIVERS];   // M422 W X Y
     #endif
   #endif
 
     #if ENABLED(Z_STEPPER_AUTO_ALIGN)
       EEPROM_WRITE(z_stepper_align.xy);
-      #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+      #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
         EEPROM_WRITE(z_stepper_align.stepper_xy);
       #endif
     #endif
 
       #if ENABLED(Z_STEPPER_AUTO_ALIGN)
         EEPROM_READ(z_stepper_align.xy);
-        #if ENABLED(Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS)
+        #if HAS_Z_STEPPER_ALIGN_STEPPER_XY
           EEPROM_READ(z_stepper_align.stepper_xy);
         #endif
       #endif

buildroot/tests/DUE

 restore_configs
 opt_set MOTHERBOARD BOARD_RADDS NUM_Z_STEPPER_DRIVERS 3
 opt_enable USE_XMAX_PLUG USE_YMAX_PLUG ENDSTOPPULLUPS BLTOUCH AUTO_BED_LEVELING_BILINEAR \
-           Z_STEPPER_AUTO_ALIGN Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS Z_SAFE_HOMING
+           Z_STEPPER_AUTO_ALIGN Z_STEPPER_ALIGN_STEPPER_XY Z_SAFE_HOMING
 pins_set ramps/RAMPS X_MAX_PIN -1
 pins_set ramps/RAMPS Y_MAX_PIN -1
 exec_test $1 $2 "RADDS with ABL (Bilinear), Triple Z Axis, Z_STEPPER_AUTO_ALIGN, E_DUAL_STEPPER_DRIVERS" "$3"