mbed-memory-status

Print thread stack, ISR stack, and global heap locations, sizes, and utilization at runtime when using mbed OS. Useful for tracking down total runtime memory usage and stack overflows.

Does not use printf(). It will automatically initialize the default serial port to 115200 8N1 using the low-level mbed serial_api.h if no other instantiation has occurred.

Example

int main()
{
    print_all_thread_info();
    print_heap_and_isr_stack_info();
}

Output

Using ARM RTX RTOS on mbed, this will print something like:

    stack ( start: 20005100 end: 20005420 size: 00000320 used: 00000070 ) thread ( id: 2000542C entry: 00020D91 )
    stack ( start: 20003D1C end: 2000451C size: 00000800 used: 00000254 ) thread ( id: 2000546C entry: 000201E1 )
    stack ( start: 20004E58 end: 20005058 size: 00000200 used: 00000050 ) thread ( id: 20005644 entry: 0002022D )
     heap ( start: 200056E8 end: 20007800 size: 00002118 used: 00000398 )  alloc ( ok: 00000006  fail: 00000000 )
isr_stack ( start: 20007800 end: 20008000 size: 00000800 used: 000002B0 )

Use

Add to your program:

mbed add https://github.com/nuket/mbed-memory-status.git mbed-memory-status

To enable the ISR stack usage tracking, the following assembly code needs to be added to your chip's specific startup_[your chip].S file:

LDR     R0, =fill_isr_stack_with_canary
BLX     R0

See the startup_example.S.txt file for what this looks like (the file is a modified copy of startup_NRF51822.S).

Then define this in mbed_memory_status.c, or via the mbed_app.json macros, or via the command line:

#define DEBUG_ISR_STACK_USAGE  1

Why

This code exists because of a stupid amount of bug-hunting:

https://vilimpoc.org/blog/2017/02/01/stack-heap-and-thread-crash-hunting-in-mbed-os/ https://vilimpoc.org/blog/2017/02/04/isr-stack-usage-on-mbed/