feat(bt): Frees BLE memory when no longer in use

          It will free libble.a & libbt all txt, data and bss segment memory.
          This memory is combined into one large memory and put into the heap
          pool.

components/bt/CMakeLists.txt

@@ -2,6 +2,7 @@ if(CONFIG_BT_ENABLED)
 
     set(srcs "")
     set(include_dirs "")
+    set(ldfragments "linker.lf")
 
     if(CONFIG_IDF_TARGET_ESP32)
         list(APPEND srcs "controller/esp32/bt.c"
@@ -18,6 +19,7 @@ if(CONFIG_BT_ENABLED)
         list(APPEND include_dirs include/esp32c3/include)
 
     elseif(CONFIG_IDF_TARGET_ESP32C2)
+        set(ldfragments "linker.lf.esp32c2")
         list(APPEND srcs "controller/esp32c2/bt.c")
         list(APPEND include_dirs include/esp32c2/include)
 
@@ -695,13 +697,12 @@ if(CONFIG_BT_ENABLED)
 
 endif()
 
-# requirements can't depend on config
 idf_component_register(SRCS "${srcs}"
-                INCLUDE_DIRS "${include_dirs}"
-                PRIV_INCLUDE_DIRS "${priv_include_dirs}"
-                REQUIRES esp_timer esp_wifi
-                PRIV_REQUIRES nvs_flash soc esp_pm esp_phy esp_coex mbedtls driver vfs
-                LDFRAGMENTS "linker.lf")
+                       INCLUDE_DIRS "${include_dirs}"
+                       PRIV_INCLUDE_DIRS "${priv_include_dirs}"
+                       REQUIRES esp_timer esp_wifi
+                       PRIV_REQUIRES nvs_flash soc esp_pm esp_phy esp_coex mbedtls driver vfs
+                       LDFRAGMENTS "${ldfragments}")
 
 if(CONFIG_BT_ENABLED)
     target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-implicit-fallthrough -Wno-unused-const-variable)

components/bt/Kconfig

@@ -68,6 +68,17 @@ menu "Bluetooth"
         source "$IDF_PATH/components/bt/controller/$IDF_TARGET/Kconfig.in"
     endmenu
 
+    config BT_RELEASE_IRAM
+        depends on BT_ENABLED && BT_LE_RELEASE_IRAM_SUPPORTED
+        bool "Release Bluetooth text (READ DOCS FIRST)"
+        default n
+        help
+            This option release Bluetooth text section and merge Bluetooth data, bss & text into
+            a large free heap region when esp_bt_mem_release is called, total saving ~21kB or more of IRAM.
+            ESP32-C2 only 3 configurable PMP entries available, rest of them are hard-coded.
+            We cannot split the memory into 3 different regions (IRAM, BLE-IRAM, DRAM).
+            So this option will disable the PMP (ESP_SYSTEM_PMP_IDRAM_SPLIT)
+
 endmenu
 
 menuconfig BLE_MESH

components/bt/controller/esp32c2/Kconfig.in

@@ -425,3 +425,6 @@ config BT_CTRL_BLE_ADV_REPORT_DISCARD_THRSHOLD
         of ADV packets lost in the controller reaches this threshold. It is better to set a larger value.
         If you set `BT_CTRL_BLE_ADV_REPORT_DISCARD_THRSHOLD` to a small value or printf every adv lost event, it
         may cause adv packets lost more.
+config BT_LE_RELEASE_IRAM_SUPPORTED
+    bool
+    default y

components/bt/controller/esp32c2/bt.c

@@ -156,14 +156,14 @@ extern int ble_txpwr_set(esp_ble_enhanced_power_type_t power_type, uint16_t hand
 extern int ble_txpwr_get(esp_ble_enhanced_power_type_t power_type, uint16_t handle);
 extern int ble_get_npl_element_info(esp_bt_controller_config_t *cfg, ble_npl_count_info_t * npl_info);
 extern void bt_track_pll_cap(void);
-extern uint32_t _bt_bss_start;
+
+#if CONFIG_BT_RELEASE_IRAM
+extern uint32_t _iram_bt_text_start;
+extern uint32_t _bss_bt_end;
+#else
 extern uint32_t _bt_bss_end;
-extern uint32_t _nimble_bss_start;
-extern uint32_t _nimble_bss_end;
-extern uint32_t _nimble_data_start;
-extern uint32_t _nimble_data_end;
-extern uint32_t _bt_data_start;
-extern uint32_t _bt_data_end;
+extern uint32_t _bt_controller_data_start;
+#endif
 
 /* Local Function Declaration
  *********************************************************************
@@ -832,32 +832,28 @@ esp_err_t esp_bt_mem_release(esp_bt_mode_t mode)
 {
     intptr_t mem_start, mem_end;
 
+#if CONFIG_BT_RELEASE_IRAM && CONFIG_ESP_SYSTEM_PMP_IDRAM_SPLIT
+    /* Release Bluetooth text section and merge Bluetooth data, bss & text into a large free heap
+     * region when esp_bt_mem_release is called, total saving ~21kB or more of IRAM. ESP32-C2 has
+     * only 3 configurable PMP entries available, rest of them are hard-coded. We cannot split the
+     * memory into 3 different regions (IRAM, BLE-IRAM, DRAM). So `ESP_SYSTEM_PMP_IDRAM_SPLIT` needs
+     * to be disabled.
+     */
+    ESP_LOGE(NIMBLE_PORT_LOG_TAG, "`ESP_SYSTEM_PMP_IDRAM_SPLIT` should be disabled!");
+    assert(0);
+#endif // CONFIG_BT_RELEASE_IRAM && CONFIG_ESP_SYSTEM_PMP_IDRAM_SPLIT
+
     if (mode & ESP_BT_MODE_BLE) {
-        mem_start = (intptr_t)&_bt_bss_start;
+#if CONFIG_BT_RELEASE_IRAM
+        mem_start = (intptr_t)MAP_IRAM_TO_DRAM((intptr_t)&_iram_bt_text_start);
+        mem_end = (intptr_t)&_bss_bt_end;
+#else
+        mem_start = (intptr_t)&_bt_controller_data_start;
         mem_end = (intptr_t)&_bt_bss_end;
+#endif // CONFIG_BT_RELEASE_IRAM
         if (mem_start != mem_end) {
-            ESP_LOGD(NIMBLE_PORT_LOG_TAG, "Release BT BSS [0x%08x] - [0x%08x]", mem_start, mem_end);
-            ESP_ERROR_CHECK(try_heap_caps_add_region(mem_start, mem_end));
-        }
-
-        mem_start = (intptr_t)&_bt_data_start;
-        mem_end = (intptr_t)&_bt_data_end;
-        if (mem_start != mem_end) {
-            ESP_LOGD(NIMBLE_PORT_LOG_TAG, "Release BT Data [0x%08x] - [0x%08x]", mem_start, mem_end);
-            ESP_ERROR_CHECK(try_heap_caps_add_region(mem_start, mem_end));
-        }
-
-        mem_start = (intptr_t)&_nimble_bss_start;
-        mem_end = (intptr_t)&_nimble_bss_end;
-        if (mem_start != mem_end) {
-            ESP_LOGD(NIMBLE_PORT_LOG_TAG, "Release NimBLE BSS [0x%08x] - [0x%08x]", mem_start, mem_end);
-            ESP_ERROR_CHECK(try_heap_caps_add_region(mem_start, mem_end));
-        }
-
-        mem_start = (intptr_t)&_nimble_data_start;
-        mem_end = (intptr_t)&_nimble_data_end;
-        if (mem_start != mem_end) {
-            ESP_LOGD(NIMBLE_PORT_LOG_TAG, "Release NimBLE Data [0x%08x] - [0x%08x]", mem_start, mem_end);
+            ESP_LOGI(NIMBLE_PORT_LOG_TAG, "Release BLE [0x%08x] - [0x%08x], len %d", mem_start,
+                     mem_end, mem_end - mem_start);
             ESP_ERROR_CHECK(try_heap_caps_add_region(mem_start, mem_end));
         }
     }

components/bt/linker.lf.esp32c2

@@ -0,0 +1,60 @@
+[sections:bt_text]
+entries:
+    .iram1+
+
+[sections:bt_bss]
+entries:
+    .bss+
+    .sbss+
+
+[sections:bt_data]
+entries:
+    .data+
+    .sdata+
+    .dram1+
+
+[sections:bt_common]
+entries:
+    COMMON
+
+[scheme:bt_start_end]
+entries:
+    bt_text -> iram0_bt_text
+    bt_bss -> dram0_bt_bss
+    bt_common -> dram0_bt_bss
+    bt_data -> dram0_bt_data
+
+# For the following fragments, order matters for
+# 'ALIGN(4) ALIGN(4, post) SURROUND(sym)', which generates:
+#
+#   . = ALIGN(4)
+#   _sym_start
+#   ...
+#   . = ALIGN(4)
+#   _sym_end
+
+[mapping:bt]
+archive: libbt.a
+entries:
+    * (bt_start_end);
+        bt_bss -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(bt_bss),
+        bt_common -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(bt_common),
+        bt_data -> dram0_bt_data  ALIGN(4) ALIGN(4, post) SURROUND(bt_data)
+    if ESP_ALLOW_BSS_SEG_EXTERNAL_MEMORY = y:
+        * (extram_bss)
+
+[mapping:btdm]
+archive: libbtdm_app.a
+entries:
+    * (bt_start_end);
+        bt_bss -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(btdm_bss),
+        bt_common -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(btdm_common),
+        bt_data -> dram0_bt_data ALIGN(4) ALIGN(4, post) SURROUND(btdm_data)
+
+[mapping:bt_controller]
+archive: libble_app.a
+entries:
+    * (bt_start_end);
+        bt_bss -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(bt_controller_bss),
+        bt_common -> dram0_bt_bss ALIGN(4) ALIGN(4, post) SURROUND(bt_controller_common),
+        bt_data -> dram0_bt_data ALIGN(4) ALIGN(4, post) SURROUND(bt_controller_data)

components/esp_system/ld/esp32c2/sections.ld.in

@@ -35,9 +35,27 @@ SECTIONS
     . = ORIGIN(dram0_0_seg) + _iram_end - _iram_start;
   } > dram0_0_seg
 
-  .dram0.data :
+  /**
+   * This section MUST be placed at the beginning of the DRAM0,
+   * which will be released along with iram0_bt.text when Bluetooth is no longer in use
+   */
+ .dram0.bt.data :
   {
     _data_start = ABSOLUTE(.);
+    mapping[dram0_bt_data]
+    . = ALIGN(8);
+  } > dram0_0_seg
+
+  .dram0.bt.bss (NOLOAD) :
+  {
+    . = ALIGN (8);
+    _bss_bt_start = ABSOLUTE(.);
+    mapping[dram0_bt_bss]
+    _bss_bt_end = ABSOLUTE(.);
+  } > dram0_0_seg
+
+  .dram0.data :
+  {
     *(.gnu.linkonce.d.*)
     *(.data1)
     __global_pointer$ = . + 0x800;
@@ -289,6 +307,18 @@ SECTIONS
     mapping[iram0_bss]
 
     _iram_bss_end = ABSOLUTE(.);
+  } > iram0_0_seg
+
+  /**
+   * This section needs to be placed at the end of the IRAM0,
+   * which will be released along with dram0_bt_data and dram0_bt_bss when Bluetooth is no longer in use
+   */
+  .iram0.bt.text :
+  {
+    . = ALIGN(16);
+    _iram_bt_text_start = ABSOLUTE(.);
+    mapping[iram0_bt_text]
+
     . = ALIGN(16);
     _iram_end = ABSOLUTE(.);
   } > iram0_0_seg

components/esp_system/port/cpu_start.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2023 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -108,7 +108,10 @@ extern int _bss_start;
 extern int _bss_end;
 extern int _rtc_bss_start;
 extern int _rtc_bss_end;
-
+#if CONFIG_BT_LE_RELEASE_IRAM_SUPPORTED
+extern int _bss_bt_start;
+extern int _bss_bt_end;
+#endif // CONFIG_BT_LE_RELEASE_IRAM_SUPPORTED
 extern int _instruction_reserved_start;
 extern int _instruction_reserved_end;
 extern int _rodata_reserved_start;
@@ -328,6 +331,11 @@ void IRAM_ATTR call_start_cpu0(void)
     //Clear BSS. Please do not attempt to do any complex stuff (like early logging) before this.
     memset(&_bss_start, 0, (&_bss_end - &_bss_start) * sizeof(_bss_start));
 
+#if CONFIG_BT_LE_RELEASE_IRAM_SUPPORTED
+    // Clear Bluetooth bss
+    memset(&_bss_bt_start, 0, (&_bss_bt_end - &_bss_bt_start) * sizeof(_bss_bt_start));
+#endif // CONFIG_BT_LE_RELEASE_IRAM_SUPPORTED
+
 #if defined(CONFIG_IDF_TARGET_ESP32) && defined(CONFIG_ESP32_IRAM_AS_8BIT_ACCESSIBLE_MEMORY)
     // Clear IRAM BSS
     memset(&_iram_bss_start, 0, (&_iram_bss_end - &_iram_bss_start) * sizeof(_iram_bss_start));

docs/en/api-guides/performance/ram-usage.rst

@@ -161,6 +161,7 @@ The following options will reduce IRAM usage of some ESP-IDF features:
     - Setting :ref:`CONFIG_HAL_DEFAULT_ASSERTION_LEVEL` to disable assertion for HAL component saves some IRAM, especially for HAL code who calls ``HAL_ASSERT`` a lot and resides in IRAM.
     - Refer to the sdkconfig menu ``Auto-detect Flash chips``, and you can disable flash drivers which you do not need to save some IRAM.
     - Enable :ref:`CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH`. Provided that :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` is not enabled and the heap functions are not incorrectly used from ISRs, this option is safe to enable in all configurations.
+    :esp32c2: - Enable :ref:`CONFIG_BT_RELEASE_IRAM`. Release BT text section and merge BT data, bss & text into a large free heap region when ``esp_bt_mem_release`` is called. This makes Bluetooth unavailable until the next restart, but saving ~22 KB or more of IRAM.
 
 .. only:: esp32
 

docs/zh_CN/api-guides/performance/ram-usage.rst

@@ -161,6 +161,7 @@ IRAM 优化
     - 设置 :ref:`CONFIG_HAL_DEFAULT_ASSERTION_LEVEL` 为禁用 HAL 组件的断言，可以节省 IRAM 空间，对于经常调用 ``HAL_ASSERT`` 且位于 IRAM 中的 HAL 代码尤为如此。
     - 要禁用不需要的 flash 驱动程序，节省 IRAM 空间，请参阅 sdkconfig 菜单中的 ``Auto-detect Flash chips`` 选项。
     - 启用 :ref:`CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH`。只要未启用 :ref:`CONFIG_SPI_MASTER_ISR_IN_IRAM` 选项，且没有从 ISR 中错误地调用堆函数，就可以在所有配置中安全启用此选项。
+    :esp32c2: - 启用 :ref:`CONFIG_BT_RELEASE_IRAM`。 蓝牙所使用的 data，bss 和 text 段已经被分配在连续的RAM区间。当调用 ``esp_bt_mem_release`` 时，这些段都会被添加到 Heap 中。 这将节省约 22 KB 的 RAM。但要再次使用蓝牙功能，需要重启程序。
 
 .. only:: esp32