On Mon, Oct 17, 2011 at 5:22 PM, Richard Henderson <r...@twiddle.net> wrote: > On 10/17/2011 07:09 AM, Bob Breuer wrote: >> I don't think this is a free/g_free issue. If I use the following >> patch, then I at least get the openbios messages: >> >> diff --git a/cpu-exec.c b/cpu-exec.c >> index a9fa608..dfbd6ea 100644 >> --- a/cpu-exec.c >> +++ b/cpu-exec.c >> @@ -180,6 +180,7 @@ static void cpu_handle_debug_exception(CPUState >> /* main execution loop */ >> >> volatile sig_atomic_t exit_request; >> +register void *ebp asm("ebp"); >> >> int cpu_exec(CPUState *env) >> { >> @@ -233,6 +234,8 @@ int cpu_exec(CPUState *env) >> >> /* prepare setjmp context for exception handling */ >> for(;;) { >> + int dummy = 0; >> + ebp = &dummy; > > See if > > asm("" : : : "ebp"); > > also solves the problem. > >> Google finds a mention of longjmp failing with -fomit-frame-pointer: >> http://lua-users.org/lists/lua-l/2005-02/msg00158.html >> >> Looks like gcc 4.6 turns on -fomit-frame-pointer by default. > > Hmm. This is the first I've heard of a longjmp implementation > failing without a frame pointer. Presumably this is with the > mingw i.e. msvc libc? > > This is something that could be worked around in gcc, I suppose. > We recognize longjmp for some things, we could force the use of > a frame pointer for msvc targets too. > > For now it might be best to simply force -fno-omit-frame-pointer > for mingw host in the configure script.
IIRC buggy versions of alloca() could also fail without a frame pointer.