This is a hardware issue and can vary between different versions. Some hardware of course generates an unhandled exception on unaligned access; some hardware generates an internally handled exception and restarts the access with a different and more expensive pathway or with microcode; some hardware efficiently handles it as it goes and has minimal impact. Sometimes this behavior is different depending on whether the hardware is in big endian vs. little endian mode. A new generation of the same processor family or a version by a different company may act differently than another. Finally, if that memory is accessed by a different means than the CPU (e.g. via DMA or the video bus), then it may require alignment where it doesn't otherwise.
What I'm getting at here is that I think we would need to be careful about disabling it for any hardware, including even forgiving hardware like x86. > On Sep 4, 2008, at 12:20 PM, Paul Pedriana wrote: > >> I'll make a patch and attach it to >> <https://bugs.webkit.org/show_bug.cgi?id=16925>, if that's OK. > > That would be great! > > One thing I'm not sure about is whether we want to enforce alignment > on platforms that don't require it - performance testing should answer > this. > > - WBR, Alexey Proskuryakov > > _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
