I was testing an idea to detect if an watcher application could save in RAM was thread was causing the watchdog reset.

The solution was easy to implement, I just reserve a area in the linkerscript:

diff --git a/boards/arm/stm32/stm32f401rc-rs485/scripts/ld.script b/boards/arm/stm32/stm32f401rc-rs485/scripts/ld.script
index 96355a3762..98eb837c92 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/scripts/ld.script
+++ b/boards/arm/stm32/stm32f401rc-rs485/scripts/ld.script
@@ -82,6 +82,10 @@ SECTIONS
         _edata = ABSOLUTE(.);
     } > sram AT > flash
 +    .no_init : {
+      *(.no_init)
+    } > sram
+
     .bss : {
         _sbss = ABSOLUTE(.);
         *(.bss .bss.*)

Then in my application I just define a variable to use that area:

diff --git a/examples/hello/hello_main.c b/examples/hello/hello_main.c
index 2cd6cb400..717f5e881 100644
--- a/examples/hello/hello_main.c
+++ b/examples/hello/hello_main.c
@@ -25,6 +25,8 @@
 #include <nuttx/config.h>
 #include <stdio.h>
 +int count __attribute__ ((section (".no_init")));
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -35,6 +37,14 @@
  int main(int argc, FAR char *argv[])
 {
-  printf("Hello, World!!\n");
+  /* Hack to initialize variable correctly first time */
+
+  if (count < 0 || count > 100)
+    {
+      count = 0;
+    }
+
+  printf("This program was executed %d times\n", ++count);
   return 0;
 }

And this was the result:

NuttShell (NSH) NuttX-12.4.0-RC0                                             
nsh> hello
This program was executed 1 times                                            
nsh> 
NuttShell (NSH) NuttX-12.4.0-RC0                                             
nsh> hello
This program was executed 2 times                                            
nsh>

Helpful resource: https://community.st.com/t5/stm32-mcus-products/how-to-retain-global-variable-after-nvic-reset-in-stm32f302r8/td-p/161899