Francois Gouget skrev: > The problem revolves around the x86 direction flag (DF), which > governs whether block memory operations operate forward through > memory or backwards. GCC [...] 4.3.0, assumes that the direction flag > has been cleared [...] at the entry of each function, as is specified > by the ABI [...] Prior to 4.3, GCC would emit a cld (clear direction > flag) opcode before doing inline string or memory operations. > > So any compiler that not clear the direction flag at the start of each > function can cause kernel crashes when running on a buggy Linux or BSD > kernel.
No, it doesn't say that. The kernel is unaffected. The problem is only with user-mode signal handlers; if DF is set when a signal occurs, the signal handler may get confused. > Does anyone know if MSVC does a cld in the right places? Maybe. But it hardly matters. Only GCC-generated code is affected. The problem might then show up in Wine signal/exception handling. Things like, say, copying the CONTEXT structures around, for example. In Wine, you can probably easily manually clear the flag on Wine signal handler entry (init_handler), if you're worried.
