diff --git a/components/esp32/Kconfig b/components/esp32/Kconfig
index 2d55676f3..12bdf7045 100644
--- a/components/esp32/Kconfig
+++ b/components/esp32/Kconfig
@@ -141,6 +141,7 @@ config MEMMAP_SPIRAM_TEST
 
 config MEMMAP_SPIRAM_ENABLE_MALLOC
     bool "malloc() can also allocate in SPI SRAM"
+    depends on !MEMMAP_SPIRAM_NO_HEAPALLOC
     default "n"
     help
         If enabled, malloc() will return pointers to both internal as well as external
diff --git a/components/esp32/heap_alloc_caps.c b/components/esp32/heap_alloc_caps.c
index fbde06614..8c26e7cec 100644
--- a/components/esp32/heap_alloc_caps.c
+++ b/components/esp32/heap_alloc_caps.c
@@ -149,6 +149,30 @@ void heap_alloc_enable_nonos_stack_tag()
     nonos_stack_in_use=false;
 }
 
+bool esp32_ptr_has_memory_caps(void *ptr, int caps) {
+    int tag=-1;
+    //Look up region tag of pointer
+    for (int i=0; regions[i].xSizeInBytes!=0; i++) {
+        if (regions[i].xTag != -1 && 
+                (uint8_t*)ptr >= regions[i].pucStartAddress && 
+                (uint8_t*)ptr < regions[i].pucStartAddress+regions[i].xSizeInBytes) {
+            tag=regions[i].xTag;
+            break;
+        }
+    }
+    if (tag==-1) return false;
+    //Mask off all the caps the tag does have. What should remain is the caps the tag does not have.
+    for (int i=0; i<NO_PRIOS; i++) caps&=~(tag_desc[tag].prio[i]);
+    //If any remain, ptr does not have all given caps.
+    return (caps==0);
+}
+
+
+bool esp32_task_stack_is_internal() {
+    int i;
+    return esp32_ptr_has_memory_caps(&i, MALLOC_CAP_INTERNAL);
+}
+
 //Modify regions array to disable the given range of memory.
 static void disable_mem_region(void *from, void *to) {
     int i;
diff --git a/components/esp32/include/esp_heap_alloc_caps.h b/components/esp32/include/esp_heap_alloc_caps.h
index da2d05e67..9b9098ebe 100644
--- a/components/esp32/include/esp_heap_alloc_caps.h
+++ b/components/esp32/include/esp_heap_alloc_caps.h
@@ -86,6 +86,26 @@ size_t xPortGetFreeHeapSizeCaps( uint32_t caps );
  */
 size_t xPortGetMinimumEverFreeHeapSizeCaps( uint32_t caps );
 
+/**
+ * @brief Checks if a memory address resides in a memory region satisfying the given capabilities
+ *
+ * Given a pointer, this routine will look up the region it resides in. If the region
+ * has _all_ the capabilities given in caps, it will return true. If this is not the case,
+ * or the pointer address is unknown , false is returned.
+ *
+ * @param ptr         Pointer to be investigated
+ * @param caps        Bitwise OR of MALLOC_CAP_* flags 
+ *
+ * @return True if pointer region has all the given capabilities
+ */
+bool esp32_ptr_has_memory_caps(void *ptr, int caps);
 
 
+/**
+ * @brief Convenience function to check if stack of currently-running task resides in internal memory
+ *
+ * @returns true if stack is in internal memory
+ */
+bool esp32_task_stack_is_internal();
+
 #endif
\ No newline at end of file
diff --git a/components/esp32/test/test_psram_cache_flush.c b/components/esp32/test/test_psram_cache_flush.c
new file mode 100644
index 000000000..4c743ca6f
--- /dev/null
+++ b/components/esp32/test/test_psram_cache_flush.c
@@ -0,0 +1,110 @@
+/*
+This code triggers a psram-related silicon bug in rev0 silicon. The bug is fixed in rev1 silicon.
+*/
+
+#include <esp_types.h>
+#include <stdio.h>
+#include "rom/ets_sys.h"
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/semphr.h"
+#include "freertos/queue.h"
+#include "freertos/xtensa_api.h"
+#include "unity.h"
+#include "soc/dport_reg.h"
+#include "soc/io_mux_reg.h"
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "rom/ets_sys.h"
+#include "esp_heap_alloc_caps.h"
+#include "esp_spi_flash.h"
+
+
+#define TSTSZ (16*1024)
+
+
+volatile static int res[2];
+
+void tstMem(void *arg) {
+	volatile unsigned char *mem=(volatile unsigned char*)arg;
+	int p=0;
+	while(1) {
+		for (int i=0; i<TSTSZ; i++) {
+			mem[i]=(i^p);
+		}
+//		vTaskDelay(1);
+		for (int i=0; i<TSTSZ; i++) {
+			if (mem[i]!=((i^p)&0xff)) {
+				printf("Core %d mem err! Got %x espected %x at addr %p\n", xPortGetCoreID(), mem[i], (i^p)&0xff, &mem[i]);
+			}
+		}
+		p++;
+		res[xPortGetCoreID()]++;
+	}
+}
+
+
+TEST_CASE("PSram cache flush on mmap", "[psram][ignore]")
+{
+    void *mem[2];
+	res[0]=0; res[1]=0;
+    mem[0]=pvPortMallocCaps(TSTSZ, MALLOC_CAP_SPIRAM);
+    mem[1]=pvPortMallocCaps(TSTSZ, MALLOC_CAP_SPIRAM);
+    TaskHandle_t th[2];
+    printf("Creating tasks\n");
+    xTaskCreatePinnedToCore(tstMem  , "tskone"  , 2048, mem[0], 3, &th[0], 0);
+    xTaskCreatePinnedToCore(tstMem  , "tsktwo"  , 2048, mem[1], 3, &th[1], 1);
+	char buf[512];
+
+	for (int i=0; i<4*1024*1024; i+=512) {
+		spi_flash_read(i, buf, 512);
+		vTaskDelay(1);
+	}
+
+	printf("Checked memory %d and %d times.\n", res[0], res[1]);
+
+	vTaskDelete(th[0]);
+	vTaskDelete(th[1]);
+	free(mem[0]);
+	free(mem[1]);
+
+}
+
+
+#define FLASHPOS (2*1024*1024-512)
+#define CYCLES 1024
+
+TEST_CASE("PSram cache flush on write/read", "[psram][ignore]")
+{
+    void *mem[2];
+	res[0]=0; res[1]=0;
+    mem[0]=pvPortMallocCaps(TSTSZ, MALLOC_CAP_SPIRAM);
+    mem[1]=pvPortMallocCaps(TSTSZ, MALLOC_CAP_SPIRAM);
+    TaskHandle_t th[2];
+    printf("Creating tasks\n");
+    xTaskCreatePinnedToCore(tstMem  , "tskone"  , 2048, mem[0], 3, &th[0], 0);
+    xTaskCreatePinnedToCore(tstMem  , "tsktwo"  , 2048, mem[1], 3, &th[1], 1);
+	char buf[512];
+
+	printf("Erasing sector...\n");
+	spi_flash_erase_sector(FLASHPOS/4096);
+	printf("Erased.\n");
+	for (int i=0; i<CYCLES; i++) {
+		printf("%d/%d\n", i, CYCLES);
+		spi_flash_write(FLASHPOS, buf, 512);
+		spi_flash_read(i, buf, 512);
+		vTaskDelay(1);
+		//if ((i%31)==0) 
+	}
+
+	printf("Checked memory %d and %d times.\n", res[0], res[1]);
+
+	vTaskDelete(th[0]);
+	vTaskDelete(th[1]);
+	free(mem[0]);
+	free(mem[1]);
+}
+
diff --git a/components/fatfs/src/vfs_fat.c b/components/fatfs/src/vfs_fat.c
index b9f5e40aa..59a6d59f0 100644
--- a/components/fatfs/src/vfs_fat.c
+++ b/components/fatfs/src/vfs_fat.c
@@ -510,7 +510,7 @@ static int vfs_fat_closedir(void* ctx, DIR* pdir)
 static struct dirent* vfs_fat_readdir(void* ctx, DIR* pdir)
 {
     vfs_fat_dir_t* fat_dir = (vfs_fat_dir_t*) pdir;
-    struct dirent* out_dirent;
+    struct dirent* out_dirent=NULL;
     int err = vfs_fat_readdir_r(ctx, pdir, &fat_dir->cur_dirent, &out_dirent);
     if (err != 0) {
         errno = err;
diff --git a/components/spi_flash/cache_utils.c b/components/spi_flash/cache_utils.c
index 6d0dd9184..a0f3b1d7a 100644
--- a/components/spi_flash/cache_utils.c
+++ b/components/spi_flash/cache_utils.c
@@ -31,7 +31,6 @@
 #include "esp_spi_flash.h"
 #include "esp_log.h"
 
-
 static void IRAM_ATTR spi_flash_disable_cache(uint32_t cpuid, uint32_t* saved_state);
 static void IRAM_ATTR spi_flash_restore_cache(uint32_t cpuid, uint32_t saved_state);
 
diff --git a/components/spi_flash/flash_mmap.c b/components/spi_flash/flash_mmap.c
index 62e617950..d4b792c39 100644
--- a/components/spi_flash/flash_mmap.c
+++ b/components/spi_flash/flash_mmap.c
@@ -32,6 +32,7 @@
 #include "esp_log.h"
 #include "cache_utils.h"
 #include "esp_psram.h"
+#include "esp_heap_alloc_caps.h"
 
 #ifndef NDEBUG
 // Enable built-in checks in queue.h in debug builds
diff --git a/components/spi_flash/flash_ops.c b/components/spi_flash/flash_ops.c
index 86101ef04..b857111c3 100644
--- a/components/spi_flash/flash_ops.c
+++ b/components/spi_flash/flash_ops.c
@@ -31,6 +31,7 @@
 #include "esp_spi_flash.h"
 #include "esp_log.h"
 #include "cache_utils.h"
+#include "esp_heap_alloc_caps.h"
 
 /* bytes erased by SPIEraseBlock() ROM function */
 #define BLOCK_ERASE_SIZE 65536
@@ -102,6 +103,7 @@ size_t IRAM_ATTR spi_flash_get_chip_size()
 
 static inline void IRAM_ATTR spi_flash_guard_start()
 {
+    assert(esp32_task_stack_is_internal() && "SPI operation called from task which has its stack in external memory");
     if (s_flash_guard_ops && s_flash_guard_ops->start) {
         s_flash_guard_ops->start();
     }
diff --git a/tools/unit-test-app/sdkconfig b/tools/unit-test-app/sdkconfig
index 54a8c7bcf..f618bbc65 100644
--- a/tools/unit-test-app/sdkconfig
+++ b/tools/unit-test-app/sdkconfig
@@ -21,12 +21,10 @@ CONFIG_LOG_BOOTLOADER_LEVEL_WARN=y
 CONFIG_LOG_BOOTLOADER_LEVEL=2
 
 #
-# Secure boot configuration
+# Security features
 #
-CONFIG_SECURE_BOOTLOADER_DISABLED=y
-# CONFIG_SECURE_BOOTLOADER_ONE_TIME_FLASH is not set
-# CONFIG_SECURE_BOOTLOADER_REFLASHABLE is not set
-# CONFIG_SECURE_BOOTLOADER_ENABLED is not set
+# CONFIG_SECURE_BOOT_ENABLED is not set
+# CONFIG_FLASH_ENCRYPTION_ENABLED is not set
 
 #
 # Serial flasher config
@@ -100,14 +98,12 @@ CONFIG_AWS_IOT_MQTT_PORT=8883
 CONFIG_BT_RESERVE_DRAM=0
 
 #
-# ESP32-specific config
+# ESP32-specific
 #
 # CONFIG_ESP32_DEFAULT_CPU_FREQ_80 is not set
 # CONFIG_ESP32_DEFAULT_CPU_FREQ_160 is not set
 CONFIG_ESP32_DEFAULT_CPU_FREQ_240=y
 CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ=240
-# CONFIG_ESP32_ENABLE_STACK_WIFI is not set
-# CONFIG_ESP32_ENABLE_STACK_BT is not set
 CONFIG_MEMMAP_SMP=y
 # CONFIG_MEMMAP_TRACEMEM is not set
 CONFIG_TRACEMEM_RESERVE_DRAM=0x0
@@ -115,14 +111,16 @@ CONFIG_TRACEMEM_RESERVE_DRAM=0x0
 # CONFIG_ESP32_ENABLE_COREDUMP_TO_UART is not set
 CONFIG_ESP32_ENABLE_COREDUMP_TO_NONE=y
 # CONFIG_ESP32_ENABLE_COREDUMP is not set
+CONFIG_MEMMAP_SPIRAM_ENABLE=y
+CONFIG_MEMMAP_SPIRAM_TYPE_ESPPSRAM32=y
+CONFIG_MEMMAP_SPIRAM_SIZE=4194304
+# CONFIG_MEMMAP_SPIRAM_NO_HEAPALLOC is not set
+CONFIG_MEMMAP_SPIRAM_TEST=y
+CONFIG_MEMMAP_SPIRAM_ENABLE_MALLOC=y
+CONFIG_MEMMAP_SPIRAM_ALLOC_LIMIT_INTERNAL=40960
 # CONFIG_TWO_MAC_ADDRESS_FROM_EFUSE is not set
 CONFIG_FOUR_MAC_ADDRESS_FROM_EFUSE=y
 CONFIG_NUMBER_OF_MAC_ADDRESS_GENERATED_FROM_EFUSE=4
-CONFIG_MEMMAP_SPIRAM_ENABLE=y
-CONFIG_MEMMAP_SPIRAM_TYPE_ESPPSRAM32=y
-CONFIG_MEMMAP_SPIRAM_TEST=y
-CONFIG_MEMMAP_SPIRAM_ENABLE_MALLOC=y
-CONFIG_MEMMAP_SPIRAM_ALLOC_LIMIT_INTERNAL=1024
 CONFIG_SYSTEM_EVENT_QUEUE_SIZE=32
 CONFIG_SYSTEM_EVENT_TASK_STACK_SIZE=2048
 CONFIG_MAIN_TASK_STACK_SIZE=4096
@@ -163,6 +161,7 @@ CONFIG_PHY_ENABLED=y
 #
 CONFIG_ESP32_PHY_CALIBRATION_AND_DATA_STORAGE=y
 # CONFIG_ESP32_PHY_INIT_DATA_IN_PARTITION is not set
+CONFIG_ESP32_PHY_MAX_WIFI_TX_POWER=20
 CONFIG_ESP32_PHY_MAX_TX_POWER=20
 # CONFIG_ETHERNET is not set
 
@@ -172,7 +171,6 @@ CONFIG_ESP32_PHY_MAX_TX_POWER=20
 # CONFIG_FREERTOS_UNICORE is not set
 CONFIG_FREERTOS_CORETIMER_0=y
 # CONFIG_FREERTOS_CORETIMER_1 is not set
-# CONFIG_FREERTOS_CORETIMER_2 is not set
 CONFIG_FREERTOS_HZ=1000
 CONFIG_FREERTOS_ASSERT_ON_UNTESTED_FUNCTION=y
 # CONFIG_FREERTOS_CHECK_STACKOVERFLOW_NONE is not set
@@ -209,7 +207,13 @@ CONFIG_LOG_COLORS=y
 CONFIG_LWIP_MAX_SOCKETS=4
 CONFIG_LWIP_THREAD_LOCAL_STORAGE_INDEX=0
 # CONFIG_LWIP_SO_REUSE is not set
+# CONFIG_LWIP_SO_RCVBUF is not set
 CONFIG_LWIP_DHCP_MAX_NTP_SERVERS=1
+# CONFIG_LWIP_IP_FRAG is not set
+# CONFIG_LWIP_IP_REASSEMBLY is not set
+CONFIG_TCP_MAXRTX=12
+CONFIG_TCP_SYNMAXRTX=6
+CONFIG_LWIP_DHCP_DOES_ARP_CHECK=y
 
 #
 # mbedTLS
@@ -223,6 +227,13 @@ CONFIG_MBEDTLS_HARDWARE_SHA=y
 CONFIG_MBEDTLS_HAVE_TIME=y
 # CONFIG_MBEDTLS_HAVE_TIME_DATE is not set
 
+#
+# OpenSSL
+#
+# CONFIG_OPENSSL_DEBUG is not set
+CONFIG_OPENSSL_ASSERT_DO_NOTHING=y
+# CONFIG_OPENSSL_ASSERT_EXIT is not set
+
 #
 # SPI Flash driver
 #