Hi all, I'm interested in being able to build-test kernels on various architectures while enabling extra warnings (make W=[123]). I'd like to be able to finish the builds and see all warnings, rather than seeing a failed build. However, GCC's -Werror is incompatible with this. There is plenty of code that will produce at least one warning, when warning verbosity is turned up. And GCC's -Werror is not guaranteed to remain stable over time; new versions may develop new warnings that may or may not be legitimate.
It seems that there are a few problem ARCHes that enable -Werror by default: SuperH (orphaned), SPARC, and MIPS. There are also a few scattered Makefiles throughout the build tree. Developers have previously tried to remove some of the worst offenders [1], but were mostly rejected [2]. It doesn't seem like we can fully prevent maintainers from enabling -Werror on their code--or even on their entire ARCH build, as with MIPS--for better or worse, so I look to other alternatives. For the easiest approach, I considered how one might add -Wno-error to the CFLAGS. 'make KCFLAGS=-Wno-error' looked promising, but KBUILD_CFLAGS is applied before the sub-directory Makefiles add their own options to ccflags-y. So it seems like others have come to the same conclusion as me: that Kbuild doesn't seem to provide a way to override the -Werror behvaior from the top level. [3][4] So, how can we fix this? -Werror may be useful in some cases to encourage developers to fix up their code immediately, but it is decidedly unhelpful when running code through analysis tools. Possibilities include: 1. make -Werror be applied only when we do not have W=[123]. [5] 2. develop a top-level override for CFLAGS that is applied *after* all sub-directory modifications 3. make -Werror opt-in / configurable, like PPC's CONFIG_PPC_WERROR (maybe make it a generic CONFIG_WERROR?), and prevent its unconditional use in Makefiles 4. better ideas? Regards, Brian [1] http://www.linux-mips.org/archives/linux-mips/2012-04/msg00179.html http://patchwork.ozlabs.org/patch/146297/ [2] http://www.linux-mips.org/archives/linux-mips/2012-05/msg00064.html [3] http://lists.linaro.org/pipermail/linaro-toolchain/2011-November/001869.html [4] http://lists.linaro.org/pipermail/linaro-dev/2011-December/008880.html [5] http://www.linux-mips.org/archives/linux-mips/2012-05/msg00070.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
