Merge pull request #7383 from jflyper/bfdev-f4-vector-table-relocation

[F4] Relocate ISR vector table to RAM

src/main/drivers/system_stm32f4xx.c

@@ -187,9 +187,12 @@ void systemInit(void)
     // cache RCC->CSR value to use it in isMPUSoftReset() and others
     cachedRccCsrValue = RCC->CSR;
 
-    /* Accounts for OP Bootloader, set the Vector Table base address as specified in .ld file */
+    // Although VTOR is already loaded with a possible vector table in RAM,
-    extern void *isr_vector_table_base;
+    // removing the call to NVIC_SetVectorTable causes USB not to become active,
+
+    extern uint8_t isr_vector_table_base;
     NVIC_SetVectorTable((uint32_t)&isr_vector_table_base, 0x0);
+
     RCC_AHB2PeriphClockCmd(RCC_AHB2Periph_OTG_FS, DISABLE);
 
     RCC_ClearFlag();

src/main/target/link/stm32_flash_f405.ld

@@ -36,5 +36,6 @@ MEMORY
 
 REGION_ALIAS("STACKRAM", CCM)
 REGION_ALIAS("FASTRAM", CCM)
+REGION_ALIAS("VECTAB", RAM)
 
 INCLUDE "stm32_flash_split.ld"

src/main/target/link/stm32_flash_split.ld

@@ -26,14 +26,25 @@ _Min_Stack_Size = 0x800; /* required amount of stack */
 /* Define output sections */
 SECTIONS
 {
-  /* The startup code goes first into FLASH */
+  /*
+   * The ISR vector table is loaded at the beginning of the FLASH,
+   * But it is linked (space reserved) at the beginning of the VECTAB region,
+   * which is aliased either to FLASH or RAM.
+   * When linked to RAM, the table can optionally be copied from FLASH to RAM
+   * for table relocation.
+   */
+
+  _isr_vector_table_flash_base = LOADADDR(.isr_vector);
+  PROVIDE (isr_vector_table_flash_base = _isr_vector_table_flash_base);
+
   .isr_vector :
   {
     . = ALIGN(4);
     PROVIDE (isr_vector_table_base = .);
     KEEP(*(.isr_vector)) /* Startup code */
     . = ALIGN(4);
-  } >FLASH
+    PROVIDE (isr_vector_table_end = .);
+  } >VECTAB AT> FLASH
 
   /* System memory (read-only bootloader) interrupt vector */
   .system_isr_vector (NOLOAD) :

src/main/target/system_stm32f4xx.c

@@ -314,6 +314,7 @@
   * @{
   */
 
+#include <string.h>
 #include "stm32f4xx.h"
 #include "system_stm32f4xx.h"
 #include "platform.h"
@@ -349,9 +350,7 @@
 
 /*!< Uncomment the following line if you need to relocate your vector Table in
      Internal SRAM. */
-/* #define VECT_TAB_SRAM */
+#define VECT_TAB_SRAM
-#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field.
-                                   This value must be a multiple of 0x200. */
 /******************************************************************************/
 
 /**
@@ -539,10 +538,20 @@ void SystemInit(void)
   //SetSysClock();
 
   /* Configure the Vector Table location add offset address ------------------*/
+
 #ifdef VECT_TAB_SRAM
-  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
+  // Copy vector table from isr_vector_table_flash_base to isr_vector_table_base.
+  // If these two regions are the same, the copy will have no effect
+  // (Happens when linker script aliases VECTAB to FLASH).
+
+  extern uint8_t isr_vector_table_flash_base;
+  extern uint8_t isr_vector_table_base;
+  extern uint8_t isr_vector_table_end;
+
+  memcpy(&isr_vector_table_base, &isr_vector_table_flash_base, &isr_vector_table_end - &isr_vector_table_base);
+  SCB->VTOR = (uint32_t)&isr_vector_table_base;
 #else
-  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
+  SCB->VTOR = (uint32_t)&isr_vector_table_flash_base;
 #endif
 
     SystemCoreClockUpdate();