Fix mbed-os-to-arduino for PortentaH7

dtcm section added too; can be used with

int testdtcm __attribute__((section (".dtcm"))) = 42;

/* copy *dtcm from flash to DTCM */
extern uintptr_t _dtcm_lma;
extern uintptr_t _sdtcm;
extern uintptr_t _edtcm;
volatile uint8_t *dst = (volatile uint8_t *)&_sdtcm;
volatile uint8_t *src = (volatile uint8_t *)&_dtcm_lma;
while ((uintptr_t)dst < (uintptr_t)&_edtcm) {
  *dst++ = *src++;
}

Serial.println(testdtcm); // will print 42
Serial.println((uintptr_t)&testdtcm, HEX); // will print somethin in rang 0x20000000

Author: facchinm

mbed-os-to-arduino

@@ -198,15 +198,21 @@ generate_flags () {
     .pdm_section (NOLOAD) : {\n \
         . = ABSOLUTE(0x3800FC00);\n \
         *(.pdm_buffer)\n \
-    } > RAM_D3"
+    } > RAM_D3\n \
+    _dtcm_lma = __etext + SIZEOF(.data);\n \
+    .dtcm : AT(_dtcm_lma) {\n \
+        _sdtcm = .;\n \
+        *(.dtcm*)\n \
+        _edtcm = .;\n \
+    } > DTCMRAM"
 				sed -i "s?.heap (COPY):?${OPENAMP_SECTION}\n    .heap (COPY):?g" $ARDUINOVARIANT/linker_script.ld
 				OPENAMP_REGIONS="__OPENAMP_region_start__  = 0x38000400;\n__OPENAMP_region_end__ = 0x38000400 + LENGTH(RAM_D3) - 1K;"
 				sed -i "s?ENTRY(Reset_Handler)?${OPENAMP_REGIONS}\nENTRY(Reset_Handler)?g" $ARDUINOVARIANT/linker_script.ld
 			fi
 			echo "Patching linker scripts"
 			sed -i 's/0x8100000/CM4_BINARY_START/g' "$ARDUINOVARIANT"/linker_script.ld
-			sed -i 's/LENGTH = 0x100000/LENGTH = CM4_BINARY_END - CM4_BINARY_START/g' "$ARDUINOVARIANT"/linker_script.ld
-			sed -i 's/LENGTH = 0xc0000/LENGTH = CM4_BINARY_START - 0x8040000/g' "$ARDUINOVARIANT"/linker_script.ld
+			sed -i 's/LENGTH = 0x200000/LENGTH = CM4_BINARY_END - CM4_BINARY_START/g' "$ARDUINOVARIANT"/linker_script.ld
+			sed -i 's/LENGTH = 0x1c0000/LENGTH = CM4_BINARY_START - 0x8040000/g' "$ARDUINOVARIANT"/linker_script.ld
 		fi
 		if [[ $ARDUINOVARIANT == *NANO_RP2040* ]]; then
 			set +e