On Wed, Apr 13, 2011 at 9:56 PM, kevin diggs <diggskevin38@xxxxxxxxx> wrote: > Even if it doesn't break it will likely incur a performance penalty > from unaligned accesses, right? Yes, in best case it will only be slow. (however, you may have a 8 bit CPU or so, needing byte-boundary alignment only :)). I had some ARM boards where things like ((struct foo*)(&recv_buf[123]))->mess.cmd do crash (but code was not generated with gcc), as far as I know it is possible that compilers generate code to access using multiple aligned access instructions, but I guess some CPUs do this internally automatically (because the same binary code did not crash on different [older/smaller/slower] ARM CPUs). So I think the code example with (struct f*)(malloc(s)+1) may run (slowly) in exceptional/lucky cases, but is not correct and should be fixed, if possible. oki, Steffen
