http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49942
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-02 13:36:53 UTC --- I think the testcase from your exec charset for Linux would map to: struct oper { char *digits; char sign; }; struct oper oper0 = {"\xf9\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0", 'N'}; struct oper oper1 = {"\xf4\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0", 'N'}; static int comp (struct oper *op0, struct oper *op1) { int i; __builtin_printf ("%s vs %s ", op0->digits, op1->digits); for (i = 0; 9 > i; i++) { int diff = (0xff & op0->digits[i]) - (0xff & op1->digits[i]); if (diff) return '`' == op0->sign ? (0 < diff ? -1 : 1) : (0 > diff ? -1 : 1); } return 0; } int main () { __builtin_printf (" is %d\n", comp (&oper0, &oper1)); __builtin_printf (" is %d\n", comp (&oper1, &oper0)); return 0; } ('0' through '9' are '\xf0' through '\xf9' apparently, and '+' is 'N' and '-' is '`'. If I run this on Linux, I still get the expected results. No idea about if zVM doesn't set up something differently etc., clearly it works on Linux. Can you use a s390x-linux targetted compiler to compile code for the VM at all, i.e. shouldn't that be a different target?