The sparse Linux trees have diverged from mainstream Linux in their handling of FPU errors. I think mainstream Linux is correct. According to the Pentium developer''s manual in section 7.1.9, a stack fault is a type of invalid operation. So stack faults will have the invalid op bit set. The attached patch restores this behavior. (Something mangled my previous inline patch, so I''m attaching this one instead. Let''s see if this one survives...) --Charles