From 56c59f60fe7d3eca9b549e550d186d620bb06a1f Mon Sep 17 00:00:00 2001
From: sl-firmware <sl-firmware@saltylab.local>
Date: Tue, 17 Mar 2026 21:39:44 -0400
Subject: [PATCH] fix: add __stack_end defsym for fault_handler MPU guard
 (Issue #678)

STM32Cube ld script provides _estack but not __stack_end. Define
__stack_end = _estack - 0x1000 (_Min_Stack_Size) via --defsym so
fault_mpu_guard_init() and fault_mem_c() can locate the stack bottom.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 platformio.ini | 1 +
 1 file changed, 1 insertion(+)

diff --git a/platformio.ini b/platformio.ini
index 82ebd17..5532f7c 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -16,3 +16,4 @@ build_flags =
     -Os
     -Wl,--defsym,_Min_Heap_Size=0x2000
     -Wl,--defsym,_Min_Stack_Size=0x1000
+    -Wl,--defsym,__stack_end=_estack-0x1000