On 12/11/12 19:10, Arnd Bergmann wrote: > On Monday 12 November 2012, James Hogan wrote: >> Note that Meta doesn't support unaligned accesses anyway so use of >> __packed on MMIO is likely broken from the outset. > > The problem is actually the opposite: Some people incorrectly annotate > structures that are always aligned to be __packed. This has no effect > on architectures that support unaligned accesses, but causes the > access to be split into byte sized loads and stores on architectures > like Meta that cannot. > > Note also that gcc is free to split any accesses for whatever reason > it deems necessary. Hmm, I found the thread "ARM unaligned MMIO access with attribute((packed))" which appears to be one of the problems you're referring to. With some experimentation I can't reproduce this kind of problem with our current compiler, but it's certainly cause for concern. Thanks James -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
