Hi Erik, yes, it's a FP stack overflow... :-) I also tried with 9front, and the error message is slightly different: ./arithchk #define IEEE_8087 #define Arith_Kind_ASL 1 arithchk 8523: suicide: sys: fp: invalid operation fppc=0x12ee status=0xb8b3 pc=0x000012f2 further checks reveal that the problem is this function: void get_nanbits(unsigned int *b, int k) { union { double d; unsigned int z[2]; } u, u1, u2; k = 2 - k; u1.z[k] = u2.z[k] = 0x7ff00000; u1.z[1-k] = u2.z[1-k] = 0; u.d = u1.d - u2.d; /* Infinity - Infinity */ <<<<<<<====== this is the FATAL ERROR. b[0] = u.z[0]; b[1] = u.z[1]; } called as getnanbits(nanbits,1) I'm sorry but I don't know how to generate the acid code. regards, Fausto 2013/11/22 erik quanstrom > > By the way I have always the same problem (suicide with stack overflow > > running arithchk). > > that's not a stack overflow, that's a x87 floating point stack overflow. > if you would post the code around the program counter in your error > message it would be helpful. asm(*PC) with acid would be even better. > > - erik >