Assembled the module ports, which no check had ever compiled

ports_module/cortex_m23/gnu/module_manager/src/tx_initialize_low_level.S

@@ -9,6 +9,8 @@
  * SPDX-License-Identifier: MIT
  **************************************************************************/
 
+// Some portions generated by Claude Code (Opus 5).
+
 
 /**************************************************************************/
 /**************************************************************************/
@@ -105,7 +107,7 @@ _tx_initialize_low_level:
 
     /* Configure SysTick.  */
     LDR     r0, =0xE000E000                         // Build address of NVIC registers
-    MOV     r1, #0                                  // Build value for SysTick reset
+    MOVS    r1, #0                                  // Build value for SysTick reset
     STR     r1, [r0, #0x10]                         // Reset SysTick Control
     STR     r1, [r0, #0x18]                         // Reset SysTick Counter Value
     LDR     r1, =SYSTICK_CYCLES

ports_module/cortex_m23/gnu/module_manager/src/tx_thread_context_restore.S

@@ -9,6 +9,8 @@
  * SPDX-License-Identifier: MIT
  **************************************************************************/
 
+// Some portions generated by Claude Code (Opus 5).
+
 
 /**************************************************************************/
 /**************************************************************************/
@@ -69,7 +71,14 @@ _tx_thread_context_restore:
     /* Call the ISR exit function to indicate an ISR is complete.  */
     PUSH    {r0, lr}                                // Save return address
     BL      _tx_execution_isr_exit                  // Call the ISR exit function
-    POP     {r0, lr}                                // Recover return address
+    POP     {r0, r1}                                // Recover r0 and the return address
+    MOV     lr, r1                                  // This core cannot POP into LR: the
+                                                    //   16-bit Thumb POP takes r0-r7 and
+                                                    //   pc only.  MOV to a high register
+                                                    //   is permitted, so restore LR from
+                                                    //   a scratch register.  r1 is free --
+                                                    //   the BL above may clobber r0-r3,
+                                                    //   which is why r0 is saved at all.
 #endif
 
     BX      lr

ports_module/cortex_m23/gnu/module_manager/src/tx_thread_context_save.S

@@ -9,6 +9,8 @@
  * SPDX-License-Identifier: MIT
  **************************************************************************/
 
+// Some portions generated by Claude Code (Opus 5).
+
 
 /**************************************************************************/
 /**************************************************************************/
@@ -69,7 +71,14 @@ _tx_thread_context_save:
     /* Call the ISR enter function to indicate an ISR is starting.  */
     PUSH    {r0, lr}                                // Save return address
     BL      _tx_execution_isr_enter                 // Call the ISR enter function
-    POP     {r0, lr}                                // Recover return address
+    POP     {r0, r1}                                // Recover r0 and the return address
+    MOV     lr, r1                                  // This core cannot POP into LR: the
+                                                    //   16-bit Thumb POP takes r0-r7 and
+                                                    //   pc only.  MOV to a high register
+                                                    //   is permitted, so restore LR from
+                                                    //   a scratch register.  r1 is free --
+                                                    //   the BL above may clobber r0-r3,
+                                                    //   which is why r0 is saved at all.
 #endif
 
     BX      lr

ports_module/cortex_m23/gnu/module_manager/src/tx_thread_secure_stack_initialize.S

@@ -9,6 +9,8 @@
  * SPDX-License-Identifier: MIT
  **************************************************************************/
 
+// Some portions generated by Claude Code (Opus 5).
+
 
 /**************************************************************************/
 /**************************************************************************/
@@ -67,7 +69,7 @@ _tx_thread_secure_stack_initialize:
     SVC     3
     CPSID   i               // Disable interrupts
 #else
-    MOV     r0, #0xFF       // Feature not enabled
+    MOVS    r0, #0xFF       // Feature not enabled
 #endif
     BX      lr
     .end

scripts/check_clang.sh

@@ -211,7 +211,13 @@ say ""
 say "== Assembly sources of every Arm gnu port =="
 
 total=0
-for dir in ports/*/gnu/src ports_smp/*/gnu/src ports_module/*/gnu/src; do
+# The module ports keep their assembly in module_manager/src, not src. This
+# glob read ports_module/*/gnu/src until 26 Aug 2026; that directory does not
+# exist, the [ -d ] guard below skipped it in silence, and 116 files across
+# nine Arm module ports were assembled by no check with either compiler. The
+# count went from 724 to 840 when the path was corrected, and three of the new
+# files did not assemble.
+for dir in ports/*/gnu/src ports_smp/*/gnu/src ports_module/*/gnu/module_manager/src; do
     [ -d "$dir" ] || continue
     core="$(echo "$dir" | cut -d/ -f2)"
     spec="${PORT_TARGET[$core]:-}"
@@ -246,7 +252,13 @@ say "== Assembly behind feature macros =="
 for macro in $FEATURE_MACROS; do
     macro_total=0
     macro_bad=0
+    # The module ports are named here for the same reason as in the stage
+    # above: they were absent from this list until 26 Aug 2026 and so read as
+    # covered. Adding them found the Cortex-M23 module manager carrying the
+    # very POP {r0, lr} this comment describes, six months after the same fix
+    # landed in its non-module sibling.
     for src in $(grep -rl "$macro" ports/*/gnu/src/*.S ports_smp/*/gnu/src/*.S \
+                 ports_module/*/gnu/module_manager/src/*.S \
                  2>/dev/null | sort); do
         core="$(echo "$src" | cut -d/ -f2)"
         spec="${PORT_TARGET[$core]:-}"

scripts/check_ports.sh

@@ -39,6 +39,11 @@
 #      body in ports/cortex_m4/ac6/inc/tx_port.h, which placed statements
 #      outside any function. See issue 569.
 #
+#   4. Lowercase .s under a gnu tree. GAS preprocesses .S and not .s, so a
+#      .s file's #ifdef blocks are assembled whichever way the macro is set.
+#      Twenty-nine files were in that state, including one non-module SMP
+#      kernel port, and only one of them failed to assemble.
+#
 # The last section reports, without failing, on port families that have no copy
 # script and so cannot be checked for reproducibility.
 #
@@ -197,7 +202,56 @@ done < <(find ports ports_arch ports_module ports_smp -name "*.h" -type f \
 [ "$orphans" -eq 0 ] && say "  ok: no port header carries code at file scope"
 
 # --------------------------------------------------------------------------
-# 4. Report only: families with no copy script.
+# 4. GNU assembly that uses the preprocessor must be named .S, not .s.
+# --------------------------------------------------------------------------
+# GAS runs the C preprocessor on .S and not on .s. In a .s file every line
+# beginning with # is just a comment, so nothing fails and nothing is
+# substituted: a #define constant reaches the assembler as an undefined
+# symbol, an #ifdef block is assembled whatever the macro says, and an
+# #if/#else pair emits *both* branches. The port silently ignores its own
+# feature macros.
+#
+# Measured 26 Aug 2026, when a corrected glob in check_clang.sh first offered
+# the module ports to a compiler. Twenty-nine files were affected, and the
+# damage was not only cosmetic:
+#
+#   ports_smp/cortex_a7_smp/gnu/src/tx_thread_smp_unprotect.s -- the only .s
+#   in a directory of twenty-one .S -- wrote the caller's LR into the
+#   protection structure on every unprotect, a store guarded by
+#   TX_MPCORE_DEBUG_ENABLE, and returned through both BX lr and MOV pc, lr.
+#
+#   ports_module/cortex_m33/.../tx_thread_stack_build.s emitted both arms of
+#   an #ifdef TX_SINGLE_MODE_SECURE, so the second LR value overwrote the
+#   first and the secure build got the non-secure one.
+#
+#   ports_module/cortex_a7/.../tx_thread_schedule.s did fail to assemble, on
+#   GCC 14.3 as well as on LLVM, because #define SYS_MODE was never expanded.
+#   That is the only one of the twenty-nine any compiler complained about.
+#
+# Only the gnu trees are checked. The IAR, Arm Compiler 5 and Keil assemblers
+# preprocess .s themselves, so the same combination is correct there, and
+# around three hundred files in this repository depend on it.
+say ""
+say "== GNU assembly using the preprocessor is named .S =="
+
+lowercase=0
+while IFS= read -r f; do
+    first="$(grep -nE '^[ \t]*#[ \t]*(define|include|if|ifdef|ifndef|else|elif|endif|undef)\b' \
+             "$f" | head -1)"
+    if [ -n "$first" ]; then
+        fail "$f: preprocessor directive in a .s file, which GAS does not preprocess"
+        echo "        line $first"
+        echo "        Rename the file to .S. Check the callers first: a build script"
+        echo "        that already names it .S is the usual sign of how this happened."
+        lowercase=$((lowercase + 1))
+    fi
+done < <(find ports ports_arch ports_module ports_smp -name "*.s" -type f \
+         -path "*/gnu/*" 2>/dev/null | sort)
+
+[ "$lowercase" -eq 0 ] && say "  ok: no .s file under a gnu tree uses the preprocessor"
+
+# --------------------------------------------------------------------------
+# 5. Report only: families with no copy script.
 # --------------------------------------------------------------------------
 # These are maintained by hand, so a fix applied to one toolchain can silently
 # miss the others. Nothing here fails the run; it is a prompt to look.