Hi Måns, On Tue, 11 Feb 2014 15:33:09 +0000, Måns Rullgård <m...@mansr.com> wrote:
> The problem is that the current settings do > the exact opposite. By using -munaligned-access by default, you are > asking the compiler to go ahead and do whatever it thinks is best, which > is sometimes to perform an intentional unaligned access. Exactly when > this will happen is largely impossible to predict. The -munaligned-access option does *not* "[ask] the compiler to go ahead and do whatever it thinks is best", it tells it to use direct native accesses when unaligned accesses are required, as opposed to splitting unaligned accesses into smaller but aligned aligned native accesses, which is what you get with -mno-unaligned-access. > To get the behaviour you desire, the code should be compiled with > -mno-unaligned-access. This tells the compiler to _never_ automatically > perform an unaligned memory access. If it thinks an address might be > unaligned, it will split the access. This shows that you really have not read my argument, in which I *did* explain why we tell the compiler *not* to split unaligned accesses into smaller correctly aligned accesses, i.e., why -munaligned-access is used. > Note also that adding -mno-unaligned-access results in exactly the same > compiler behaviour as we always had prior to gcc 4.7, which presumably > generated usable code. And hid potential unaligned accesses which would harm some other platforms, because not all platforms have -m[no-]unaligned-access or even a concept of unaligned access. Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
