zephyrproject-rtos · wmrsouza · Sep 18, 2025
diff --git a/boards/espressif/esp32_devkitc/esp32_devkitc_procpu.yaml b/boards/espressif/esp32_devkitc/esp32_devkitc_procpu.yaml
@@ -19,4 +19,5 @@ supported:
   - counter
   - entropy
   - input
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32_ethernet_kit/esp32_ethernet_kit_procpu.yaml b/boards/espressif/esp32_ethernet_kit/esp32_ethernet_kit_procpu.yaml
@@ -11,4 +11,5 @@ supported:
   - nvs
   - pwm
   - i2s
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32c3_devkitc/esp32c3_devkitc.yaml b/boards/espressif/esp32c3_devkitc/esp32c3_devkitc.yaml
@@ -15,4 +15,5 @@ supported:
   - spi
   - counter
   - entropy
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32c3_devkitm/esp32c3_devkitm.yaml b/boards/espressif/esp32c3_devkitm/esp32c3_devkitm.yaml
@@ -16,4 +16,5 @@ supported:
   - spi
   - counter
   - entropy
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32c3_rust/esp32c3_rust.yaml b/boards/espressif/esp32c3_rust/esp32c3_rust.yaml
@@ -18,4 +18,5 @@ supported:
   - spi
   - counter
   - entropy
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32c6_devkitc/esp32c6_devkitc_hpcore.yaml b/boards/espressif/esp32c6_devkitc/esp32c6_devkitc_hpcore.yaml
@@ -18,6 +18,7 @@ supported:
   - i2c
   - i2s
   - netif:openthread
+  - retained_mem
 
 testing:
   ignore_tags:

diff --git a/boards/espressif/esp32h2_devkitm/esp32h2_devkitm.yaml b/boards/espressif/esp32h2_devkitm/esp32h2_devkitm.yaml
@@ -18,3 +18,4 @@ supported:
   - i2c
   - i2s
   - netif:openthread
+  - retained_mem
diff --git a/boards/espressif/esp32s2_devkitc/esp32s2_devkitc.yaml b/boards/espressif/esp32s2_devkitc/esp32s2_devkitc.yaml
@@ -20,6 +20,7 @@ supported:
   - input
   - can
   - dma
+  - retained_mem
 testing:
   ignore_tags:
     - bluetooth

diff --git a/boards/espressif/esp32s2_saola/esp32s2_saola.yaml b/boards/espressif/esp32s2_saola/esp32s2_saola.yaml
@@ -18,6 +18,7 @@ supported:
   - counter
   - entropy
   - input
+  - retained_mem
 testing:
   ignore_tags:
     - bluetooth

diff --git a/boards/espressif/esp32s3_devkitc/esp32s3_devkitc_procpu.yaml b/boards/espressif/esp32s3_devkitc/esp32s3_devkitc_procpu.yaml
@@ -17,4 +17,5 @@ supported:
   - pwm
   - dma
   - input
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32s3_devkitm/esp32s3_devkitm_procpu.yaml b/boards/espressif/esp32s3_devkitm/esp32s3_devkitm_procpu.yaml
@@ -18,4 +18,5 @@ supported:
   - dma
   - input
   - video
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp32s3_eye/esp32s3_eye_procpu.yaml b/boards/espressif/esp32s3_eye/esp32s3_eye_procpu.yaml
@@ -18,4 +18,5 @@ supported:
   - dma
   - input
   - video
+  - retained_mem
 vendor: espressif
diff --git a/boards/espressif/esp_wrover_kit/esp_wrover_kit_procpu.yaml b/boards/espressif/esp_wrover_kit/esp_wrover_kit_procpu.yaml
@@ -17,4 +17,5 @@ supported:
   - spi
   - counter
   - entropy
+  - retained_mem
 vendor: espressif
diff --git a/dts/riscv/espressif/esp32c3/esp32c3_common.dtsi b/dts/riscv/espressif/esp32c3/esp32c3_common.dtsi
@@ -100,6 +100,12 @@
 			zephyr,memory-region = "SRAM1";
 		};
 
+		rtc_fast_ram: memory@50000000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x50000000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_FAST_RAM";
+		};
+
 		intc: interrupt-controller@600c2000 {
 			compatible = "espressif,esp32-intc";
 			#address-cells = <0>;

diff --git a/dts/riscv/espressif/esp32c6/esp32c6_common.dtsi b/dts/riscv/espressif/esp32c6/esp32c6_common.dtsi
@@ -103,7 +103,7 @@
 			#address-cells = <1>;
 			#size-cells = <1>;
 			compatible = "zephyr,memory-region", "mmio-sram";
-			reg = <0x50000000 DT_SIZE_K(16)>;
+			reg = <0x50000000 (DT_SIZE_K(16) - 0x10)>;
 			zephyr,memory-region = "SRAMLP ";
 
 			shmlp: memory@50003fe0 {

diff --git a/dts/xtensa/espressif/esp32/esp32_common.dtsi b/dts/xtensa/espressif/esp32/esp32_common.dtsi
@@ -138,6 +138,18 @@
 			};
 		};
 
+		rtc_fast_ram: memory@3ff80000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x3ff80000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_FAST_RAM";
+		};
+
+		rtc_slow_ram: memory@50000000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x50000000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_SLOW_RAM";
+		};
+
 		icache0: icache0@400d0000 {
 			compatible = "zephyr,memory-region", "mmio-sram";
 			reg = <0x400d0000 DT_SIZE_K(11456)>;

diff --git a/dts/xtensa/espressif/esp32s2/esp32s2_common.dtsi b/dts/xtensa/espressif/esp32s2/esp32s2_common.dtsi
@@ -116,6 +116,18 @@
 			};
 		};
 
+		rtc_fast_ram: memory@3ff9e000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x3ff9e000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_FAST_RAM";
+		};
+
+		rtc_slow_ram: memory@50000000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x50000000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_SLOW_RAM";
+		};
+
 		icache0: icache0@40080000 {
 			compatible = "zephyr,memory-region";
 			reg = <0x40080000 DT_SIZE_K(7680)>;

diff --git a/dts/xtensa/espressif/esp32s3/esp32s3_common.dtsi b/dts/xtensa/espressif/esp32s3/esp32s3_common.dtsi
@@ -161,6 +161,18 @@
 			#mbox-cells = <1>;
 		};
 
+		rtc_slow_ram: memory@50000000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x50000000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_SLOW_RAM";
+		};
+
+		rtc_fast_ram: memory@600fe000 {
+			compatible = "zephyr,memory-region", "mmio-sram";
+			reg = <0x600fe000 DT_SIZE_K(8)>;
+			zephyr,memory-region = "RTC_FAST_RAM";
+		};
+
 		intc: interrupt-controller@600c2000 {
 			#interrupt-cells = <3>;
 			#address-cells = <0>;

diff --git a/soc/espressif/esp32/default.ld b/soc/espressif/esp32/default.ld
@@ -34,6 +34,14 @@ procpu_ext_ram_org = DCACHE1_START;
 procpu_ext_ram_len = DCACHE1_SIZE;
 #endif
 
+/* RTC RAM memory segments */
+rtc_slow_org = RCT_SLOW_RAM_START;
+rtc_slow_len = RCT_SLOW_RAM_SIZE;
+rtc_data_org = RCT_FAST_RAM_START;
+rtc_data_len = RCT_FAST_RAM_SIZE;
+rtc_iram_org = RCT_FAST_RAM_START + 0x140000;
+rtc_iram_len = RCT_FAST_RAM_SIZE;
+
 /* Aliases */
 #define FLASH_CODE_REGION irom0_0_seg
 #define RODATA_REGION     drom0_0_seg
@@ -87,9 +95,9 @@ MEMORY
   irom0_0_seg(RX): org = procpu_irom_org, len = procpu_irom_len
   drom0_0_seg(R):  org = procpu_drom_org, len = procpu_drom_len
 
-  rtc_iram_seg(RWX): org = 0x400c0000, len = 0x2000
-  rtc_slow_seg(RW):  org = 0x50000000, len = 0x2000 - CONFIG_RESERVE_RTC_MEM
-  rtc_data_seg(RW):  org = 0x3ff80000, len = 0x2000
+  rtc_iram_seg(RWX): org = rtc_iram_org, len = rtc_iram_len
+  rtc_slow_seg(RW):  org = rtc_slow_org, len = rtc_slow_len - CONFIG_RESERVE_RTC_MEM
+  rtc_data_seg(RW):  org = rtc_data_org, len = rtc_data_len
 
   /* We reduced the size of rtc_slow_seg by CONFIG_RESERVE_RTC_MEM value.
    *  It reserves the amount of RTC slow memory that we use for this memory segment.
@@ -98,7 +106,7 @@ MEMORY
    *  org = 0x50000000 + 0x2000 - CONFIG_RESERVE_RTC_MEM
    */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  rtc_slow_reserved_seg(RW): org = 0x50000000 + 0x2000 - CONFIG_RESERVE_RTC_MEM,
+  rtc_slow_reserved_seg(RW): org = rtc_slow_org + rtc_slow_len - CONFIG_RESERVE_RTC_MEM,
                              len = CONFIG_RESERVE_RTC_MEM
 #endif
 

diff --git a/soc/espressif/esp32/memory.h b/soc/espressif/esp32/memory.h
@@ -26,6 +26,14 @@
 #define SRAM2_DRAM_USER_START (SRAM2_DRAM_START + SRAM2_DRAM_SHM_SIZE)
 #define SRAM2_DRAM_USER_SIZE  (SRAM2_DRAM_END - SRAM2_DRAM_USER_START)
 
+/* RTC SLOW RAM (8kB) */
+#define RCT_SLOW_RAM_START DT_REG_ADDR(DT_NODELABEL(rtc_slow_ram))
+#define RCT_SLOW_RAM_SIZE  DT_REG_SIZE(DT_NODELABEL(rtc_slow_ram))
+
+/* RTC FAST RAM (8kB) */
+#define RCT_FAST_RAM_START DT_REG_ADDR(DT_NODELABEL(rtc_fast_ram))
+#define RCT_FAST_RAM_SIZE  DT_REG_SIZE(DT_NODELABEL(rtc_fast_ram))
+
 /** Simplified memory map for the bootloader.
  *  Make sure the bootloader can load into main memory without overwriting itself.
  *

diff --git a/soc/espressif/esp32c3/default.ld b/soc/espressif/esp32c3/default.ld
@@ -28,6 +28,10 @@ user_idram_size = (user_dram_end - user_dram_seg_org);
 user_iram_seg_len = user_idram_size;
 user_dram_seg_len = user_idram_size;
 
+/* RTC RAM memory segment */
+rtc_iram_org = RCT_FAST_RAM_START;
+rtc_iram_len = RCT_FAST_RAM_SIZE;
+
 /* Aliases */
 #define FLASH_CODE_REGION  irom0_0_seg
 #define RODATA_REGION      drom0_0_seg
@@ -73,7 +77,7 @@ MEMORY
   irom0_0_seg(RX): org = IROM_SEG_ORG, len = IROM_SEG_LEN
   drom0_0_seg (R): org = DROM_SEG_ORG, len = DROM_SEG_LEN
 
-  rtc_iram_seg(RWX): org = 0x50000000, len = 0x2000 - CONFIG_RESERVE_RTC_MEM
+  rtc_iram_seg(RWX): org = rtc_iram_org, len = rtc_iram_len - CONFIG_RESERVE_RTC_MEM
 
   /* We reduced the size of rtc_iram_seg by CONFIG_RESERVE_RTC_MEM value.
      It reserves the amount of RTC fast memory that we use for this memory segment.
@@ -82,7 +86,7 @@ MEMORY
      The aim of this is to keep data that will not be moved around and have a fixed address.
   */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  rtc_reserved_seg(RW): org = 0x50000000 + 0x2000 - CONFIG_RESERVE_RTC_MEM,
+  rtc_reserved_seg(RW): org = rtc_iram_org + rtc_iram_len - CONFIG_RESERVE_RTC_MEM,
                         len = CONFIG_RESERVE_RTC_MEM
 #endif
 

diff --git a/soc/espressif/esp32c3/memory.h b/soc/espressif/esp32c3/memory.h
@@ -13,6 +13,9 @@
 #define SRAM1_SIZE         DT_REG_SIZE(DT_NODELABEL(sram1))
 /* ICache size is fixed to 16KB on ESP32-C3 */
 #define ICACHE_SIZE        SRAM0_SIZE
+/* RTC FAST RAM (8kB) */
+#define RCT_FAST_RAM_START DT_REG_ADDR(DT_NODELABEL(rtc_fast_ram))
+#define RCT_FAST_RAM_SIZE  DT_REG_SIZE(DT_NODELABEL(rtc_fast_ram))
 
 /** Simplified memory map for the bootloader.
  *  Make sure the bootloader can load into main memory without overwriting itself.

diff --git a/soc/espressif/esp32c6/default.ld b/soc/espressif/esp32c6/default.ld
@@ -68,11 +68,11 @@ MEMORY
   drom0_0_seg(R):  org = DROM_SEG_ORG, len = DROM_SEG_LEN
 
 #if CONFIG_ULP_COPROC_ENABLED
-  lp_ram_seg(RW):    org = LPSRAM_IRAM_START + ULP_COPROC_RESERVE_MEM,
-                     len = LPSRAM_SIZE - ULP_COPROC_RESERVE_MEM - CONFIG_RESERVE_RTC_MEM
+  lp_ram_seg(RW):  org = LPSRAM_IRAM_START + ULP_COPROC_RESERVE_MEM,
+                   len = LPSRAM_SIZE - ULP_COPROC_RESERVE_MEM - CONFIG_RESERVE_RTC_MEM
 #else
-  lp_ram_seg(RW):    org = LPSRAM_IRAM_START,
-                     len = 0x4000 - CONFIG_RESERVE_RTC_MEM
+  lp_ram_seg(RW):  org = LPSRAM_IRAM_START,
+                   len = LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM
 #endif
   /* We reduced the size of lp_ram_seg by CONFIG_RESERVE_RTC_MEM value.
      It reserves the amount of LP memory that we use for this memory segment.
@@ -82,8 +82,13 @@ MEMORY
      The aim of this is to keep data that will not be moved around and have a fixed address.
   */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  lp_reserved_seg(RW) :  org = LPSRAM_IRAM_START + 0x4000 - CONFIG_RESERVE_RTC_MEM,
-                         len = CONFIG_RESERVE_RTC_MEM
+#if CONFIG_ULP_COPROC_ENABLED
+  lp_reserved_seg(RW): org = LPSRAM_IRAM_START + LPSRAM_SIZE - ULP_COPROC_RESERVE_MEM - CONFIG_RESERVE_RTC_MEM,
+                       len = CONFIG_RESERVE_RTC_MEM
+#else
+  lp_reserved_seg(RW): org = LPSRAM_IRAM_START + LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM,
+                       len = CONFIG_RESERVE_RTC_MEM
+#endif
 #endif
 
 #ifdef CONFIG_GEN_ISR_TABLES

diff --git a/soc/espressif/esp32h2/default.ld b/soc/espressif/esp32h2/default.ld
@@ -67,8 +67,8 @@ MEMORY
   irom0_0_seg(RX): org = IROM_SEG_ORG, len = IROM_SEG_LEN
   drom0_0_seg(R):  org = DROM_SEG_ORG, len = DROM_SEG_LEN
 
-  lp_ram_seg(RW):    org = LPSRAM_IRAM_START,
-                     len = LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM
+  lp_ram_seg(RW):  org = LPSRAM_IRAM_START,
+                   len = LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM
 
   /* We reduced the size of lp_ram_seg by CONFIG_RESERVE_RTC_MEM value.
      It reserves the amount of LP memory that we use for this memory segment.
@@ -78,8 +78,8 @@ MEMORY
      The aim of this is to keep data that will not be moved around and have a fixed address.
   */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  lp_reserved_seg(RW) :  org = LPSRAM_IRAM_START + LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM,
-                         len = CONFIG_RESERVE_RTC_MEM
+  lp_reserved_seg(RW): org = LPSRAM_IRAM_START + LPSRAM_SIZE - CONFIG_RESERVE_RTC_MEM,
+                       len = CONFIG_RESERVE_RTC_MEM
 #endif
 
 #ifdef CONFIG_GEN_ISR_TABLES

diff --git a/soc/espressif/esp32s2/default.ld b/soc/espressif/esp32s2/default.ld
@@ -40,6 +40,14 @@ ext_ram_org = DCACHE1_START;
 ext_ram_len = DCACHE1_SIZE;
 #endif
 
+/* RTC RAM memory segments */
+rtc_slow_org = RCT_SLOW_RAM_START;
+rtc_slow_len = RCT_SLOW_RAM_SIZE;
+rtc_data_org = RCT_FAST_RAM_START;
+rtc_data_len = RCT_FAST_RAM_SIZE;
+rtc_iram_org = RCT_FAST_RAM_START + 0xd2000;
+rtc_iram_len = RCT_FAST_RAM_SIZE;
+
 /* Aliases */
 #define FLASH_CODE_REGION irom0_0_seg
 #define RODATA_REGION     drom0_0_seg
@@ -83,9 +91,9 @@ MEMORY
   irom0_0_seg(RX): org = user_irom_org, len = user_irom_len
   drom0_0_seg(R):  org = user_drom_org, len = user_drom_len
 
-  rtc_iram_seg(RWX): org = 0x40070000, len = 0x2000 - CONFIG_RESERVE_RTC_MEM
-  rtc_slow_seg(RW):  org = 0x50000000, len = 0x2000
-  rtc_data_seg(RW) : org = 0x3ff9e000, len = 0x2000 - CONFIG_RESERVE_RTC_MEM
+  rtc_iram_seg(RWX): org = rtc_iram_org, len = rtc_iram_len - CONFIG_RESERVE_RTC_MEM
+  rtc_slow_seg(RW):  org = rtc_slow_org, len = rtc_slow_len
+  rtc_data_seg(RW):  org = rtc_data_org, len = rtc_data_len - CONFIG_RESERVE_RTC_MEM
 
   /* We reduced the size of rtc_data_seg and rtc_iram_seg by CONFIG_RESERVE_RTC_MEM value.
      It reserves the amount of RTC fast memory that we use for this memory segment.
@@ -95,7 +103,7 @@ MEMORY
      The aim of this is to keep data that will not be moved around and have a fixed address.
   */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  rtc_reserved_seg(RW): org = 0x3ff9e000 + 0x2000 - CONFIG_RESERVE_RTC_MEM,
+  rtc_reserved_seg(RW): org = rtc_data_org + rtc_data_len - CONFIG_RESERVE_RTC_MEM,
                         len = CONFIG_RESERVE_RTC_MEM
 #endif
 

diff --git a/soc/espressif/esp32s2/memory.h b/soc/espressif/esp32s2/memory.h
@@ -11,6 +11,14 @@
 #define SRAM_DRAM_START  DT_REG_ADDR(DT_NODELABEL(sram0))
 #define SRAM_CACHE_SIZE  (CONFIG_ESP32S2_INSTRUCTION_CACHE_SIZE + CONFIG_ESP32S2_DATA_CACHE_SIZE)
 
+/* RTC SLOW RAM (8k) */
+#define RCT_SLOW_RAM_START DT_REG_ADDR(DT_NODELABEL(rtc_slow_ram))
+#define RCT_SLOW_RAM_SIZE  DT_REG_SIZE(DT_NODELABEL(rtc_slow_ram))
+
+/* RTC FAST RAM (8k) */
+#define RCT_FAST_RAM_START DT_REG_ADDR(DT_NODELABEL(rtc_fast_ram))
+#define RCT_FAST_RAM_SIZE  DT_REG_SIZE(DT_NODELABEL(rtc_fast_ram))
+
 /** Simplified memory map for the bootloader.
  *  Make sure the bootloader can load into main memory without overwriting itself.
  *

diff --git a/soc/espressif/esp32s3/default.ld b/soc/espressif/esp32s3/default.ld
@@ -37,6 +37,12 @@ procpu_ext_iram_org = procpu_irom_org;
 procpu_ext_iram_len = CONFIG_ESP_SPIRAM_SIZE;
 #endif
 
+/* RTC RAM memory segments */
+rtc_iram_org = RCT_FAST_RAM_START;
+rtc_iram_len = RCT_FAST_RAM_SIZE;
+rtc_slow_org = RCT_SLOW_RAM_START;
+rtc_slow_len = RCT_SLOW_RAM_SIZE;
+
 /* Aliases */
 #define FLASH_CODE_REGION irom0_0_seg
 #define RODATA_REGION     drom0_0_seg
@@ -95,7 +101,7 @@ MEMORY
 #endif
 
   /* RTC fast memory (executable). Persists over deep sleep. */
-  rtc_iram_seg(RWX): org = 0x600fe000, len = 0x2000 - CONFIG_RESERVE_RTC_MEM
+  rtc_iram_seg(RWX): org = rtc_iram_org, len = rtc_iram_len - CONFIG_RESERVE_RTC_MEM
 
   /* We reduced the size of rtc_iram_seg by CONFIG_RESERVE_RTC_MEM value.
    * It reserves the amount of RTC fast memory that we use for this memory segment.
@@ -105,12 +111,12 @@ MEMORY
    * The aim of this is to keep data that will not be moved around and have a fixed address.
    */
 #if (CONFIG_RESERVE_RTC_MEM > 0)
-  rtc_reserved_seg(RW): org = 0x600fe000 + 0x2000 - CONFIG_RESERVE_RTC_MEM,
+  rtc_reserved_seg(RW): org = rtc_iram_org + rtc_iram_len - CONFIG_RESERVE_RTC_MEM,
                         len = CONFIG_RESERVE_RTC_MEM
 #endif
 
   /* RTC slow memory (data accessible). Persists over deep sleep. */
-  rtc_slow_seg(RW): org = 0x50000000, len = 0x2000
+  rtc_slow_seg(RW): org = rtc_slow_org, len = rtc_slow_len
 
 #ifdef CONFIG_GEN_ISR_TABLES
   IDT_LIST(RW): org = 0x3ebfe010, len = 0x2000
-Original file line number
+Diff line change
@@ Expand Up / @@ -19,4 +19,5 @@ supported: @@
       - counter
       - entropy
       - input
+      - retained_mem
     vendor: espressif