How to change compile level in GCC_RELEASE(hp)?

I don't know how to change compile level in GCC_RELEASE(hp).

There're few ways I have been tried but all failed, test with a global vriable:

Changed all the Os to O0 in every related Makefile.
Defined a global variable with __attribute__ ((optimize("O0"))), e.g., volatile char *s __attribute__ ((optimize("O0"))) = "Hello World string from KM4";, after flashing and entering gdb shell, tried to print the variable but no symbol Once the variable is used, such as printf, DiagPrintf("The km4_string is : %s\n", s);it can keep away from being optimized,

Surrounded the global vriable by pragma

#pragma GCC push_options
#pragma GCC optimize ("O0")
char *s = "Hello World string from KM4";
#pragma GCC pop_options

I also noted the compile option has been changed from "O2" to "Os" in Git 210714_317d518b to Git 210809_a30eac93 but I have no idea what to do.

Thanks in advance.

ambiot / ambd_sdk