ts wrote:
> 
>  If I'm right, it's r12

(gdb) p rb_gc_stack_start
$1 = (VALUE *) 0x60000fffffffb168
(gdb) info register r12
r12            0x60000fffffea17a0       6917546619825690528
(gdb) p (0x60000fffffffb168-0x60000fffffea17a0)/4
$2 = 353906
(gdb)  p (0x60000fffffffb168-0x60000fffffea17a0)/8
$3 = 176953
(gdb) p STACK_LEVEL_MAX
$4 = 49152

-- 
Bil Kleb, Hampton, Virginia