Hi. 2017-04-06 4:11 GMT+09:00 Michael Davidson <md@xxxxxxxxxx>: > It "works" for the cases that I currently care about but I have to say > that I am uneasy about adding -Werror to the cc-option test in this > way. > > Suppose that one of the *other* flags that is implicitly passed to the > compiler by cc-option - eg something that was explicitly specified in > $(KBUILD_CFLAGS) - triggers a warning. In that case all calls to > cc-option will silently fail because of the -Werror and valid options > will not be detected correctly. Theoretically, options explicitly specified in KBUILD_CFLAGS should be always valid. Options that may not be supported in some cases should be wrapped with $(call cc-option ). > If everyone is OK with that because "it shouldn't normally ever > happen" then that is fine, but if does result in a subtle change from > existing behavior (and a trap that I almost immediately fell into > after applying a similar patch). There is a rare case where a particular combination fails (such as the conflict between -pg and -ffunction-sections as reported in https://patchwork.kernel.org/patch/9624573/). In a such case, we may end up with swapping the order, but this should not happen quite often. > On Wed, Apr 5, 2017 at 12:01 PM, Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote: >> Hi Masahiro, >> >> El Thu, Apr 06, 2017 at 03:08:26AM +0900 Masahiro Yamada ha dit: >> >>> 2017-03-17 9:15 GMT+09:00 Michael Davidson <md@xxxxxxxxxx>: >>> > Unfortunately, while clang generates a warning about these flags >>> > being unsupported it still exits with a status of 0 so we have >>> > to explicitly disable them instead of just using a cc-option check. >>> > >>> > Signed-off-by: Michael Davidson <md@xxxxxxxxxx> >>> >>> >>> Instead, does the following work for you? >>> https://patchwork.kernel.org/patch/9657285/ >> >> Thanks for the pointer, I was about to give this change (or rather its >> ancestor) a rework myself :) >> >>> You need to use >>> $(call cc-option, ...) >>> for -falign-jumps=1 and -falign-loops=1 >> >> I can confirm that this works. >> >> Thanks >> >> Matthias > -- > To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards Masahiro Yamada
