esp32: Bootloader wake deep sleep stub
App can contain a stub program resident in RTC fast memory. Bootloader
will load the stub on initial boot. If the device wakes from deep sleep,
the stub is run immediately (before any other data is loaded, etc.)
To implement a custom wake stub, implement a function in your program:
```
void RTC_IRAM_ATTR esp_wake_deep_sleep(void)
{
esp_default_wake_deep_sleep();
// other wake logic
}
```
... and it will replace the default implementation.
See merge request !78
1. This is just a temporary solution, it will be removed when umm_malloc is ready
2. Support memory canaries mechanism
2. Add debug code to show allocated memory info
The thread-local-storage feature in FreeRTOS attaches an application-usable array of pointers to a thread control block. These pointers usually point to a structure the thread allocates. When a thread gets (voluntarily or involuntarily) destroyed, this memory can leak. This merge adds a matching second array of user-settable pointers to destructor routines. As soon as the task gets cleaned up (which happens in the idle thread), the destructors get called and the memory can be freed.
See merge request !19