main: Explicitly set the stack top based on _estack

.. setting it based on the ad-hoc stack pointer calculation of
mp_stack_ctrl_init() meant that the stack used above main() counts
against the 1KiB safety factor that the mp_stack_set_limit call tries
to establish.  It turns out, at least on M4, that over half of the
safety factor is used up by stack-above-main()!

In the case of the basics/gen_stack_overflow.py test,
which blows the stack on purpose, it turns out that gc would be called
while handling the "maximum recursion depth exceeded" error, and this
needed more stack than was left.

Closes: #900
This commit is contained in:
Jeff Epler 2018-06-05 22:04:30 -05:00
parent 74ced174ce
commit a4e06bd998
1 changed files with 1 additions and 1 deletions

2
main.c
View File

@ -241,7 +241,7 @@ int __attribute__((used)) main(void) {
// Stack limit should be less than real stack size, so we have a chance
// to recover from limit hit. (Limit is measured in bytes.)
mp_stack_ctrl_init();
mp_stack_set_top((char*)&_estack);
mp_stack_set_limit((char*)&_estack - (char*)&_ebss - 1024);
#if MICROPY_MAX_STACK_USAGE