bootloader: Fix "skip validate on exit deep sleep" when "Use RTC fast memory as heap" is enabled

RTC region used to store boot partition needs to remain reserved in the app.

components/bootloader_support/src/bootloader_common_loader.c

@@ -30,6 +30,7 @@
 #include "soc/gpio_periph.h"
 #include "soc/rtc.h"
 #include "soc/efuse_reg.h"
+#include "soc/soc_memory_layout.h"
 #include "hal/gpio_ll.h"
 #include "esp_image_format.h"
 #include "bootloader_sha.h"
@@ -138,7 +139,18 @@ esp_err_t bootloader_common_get_partition_description(const esp_partition_pos_t
 
 #if defined( CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP ) || defined( CONFIG_BOOTLOADER_CUSTOM_RESERVE_RTC )
 
-rtc_retain_mem_t *const rtc_retain_mem = (rtc_retain_mem_t *)(SOC_RTC_DRAM_HIGH - sizeof(rtc_retain_mem_t));
+#define RTC_RETAIN_MEM_ADDR (SOC_RTC_DATA_HIGH - sizeof(rtc_retain_mem_t))
+
+rtc_retain_mem_t *const rtc_retain_mem = (rtc_retain_mem_t *)RTC_RETAIN_MEM_ADDR;
+
+#if !IS_BOOTLOADER_BUILD
+/* The app needs to be told this memory is reserved, important if configured to use RTC memory as heap.
+
+   Note that keeping this macro here only works when other symbols in this file are referenced by the app, as
+   this feature is otherwise 100% part of the bootloader. However this seems to happen in all apps.
+ */
+SOC_RESERVE_MEMORY_REGION(RTC_RETAIN_MEM_ADDR, RTC_RETAIN_MEM_ADDR + sizeof(rtc_retain_mem_t), rtc_retain_mem);
+#endif
 
 static bool check_rtc_retain_mem(void)
 {