[Buildroot] [PATCH v4 02/15] linux: disable Werror for powerpc kernels

[Baruch Siach <baruch@tkos.co.il>]

Hi Peter,

On Mon, Jun 24 2019, Peter Korsgaard wrote:

>>>>>> "Giulio" == Giulio Benetti <giulio.benetti@micronovasrl.com> writes:
>
>  > From: Romain Naour <romain.naour@gmail.com>
>  > From patch [1] included in kernel >= 5.0:
>  > "The upcoming GCC 9 release extends the -Wmissing-attributes warnings
>  > (enabled by -Wall) to C and aliases: it warns when particular function
>  > attributes are missing in the aliases but not in their target.
>
>  > In particular, it triggers for all the init/cleanup_module
>  > aliases in the kernel (defined by the module_init/exit macros),
>  > ending up being very noisy.
>
>  > These aliases point to the __init/__exit functions of a module,
>  > which are defined as __cold (among other attributes). However,
>  > the aliases themselves do not have the __cold attribute.
>
>  > Since the compiler behaves differently when compiling a __cold
>  > function as well as when compiling paths leading to calls
>  > to __cold functions, the warning is trying to point out
>  > the possibly-forgotten attribute in the alias."
>
>  > Werror is set by default while building ppc kernel [2], but
>  > some warning can be introduced while building current kernel with
>  > newer compiler (for example building kernel 4.19 with gcc 9.1).
>
>  > For the same reason why we remove Werror in packages's compiler
>  > flags. Building with Werror is not bulletproof when we start
>  > using a newer compiler that introduce new warnings.
>  > This is the case here.
>
>  > Also this option is a bit strange since it's specific to ppc kernels:
>  > "The intention is to make it harder for people to inadvertantly
>  > introduce warnings in the arch/powerpc code."
>  > Other kernel developers on other arch may be interested by a
>  > similar/more generic option.
>
>  > So, It's clearly intended for kernel developers.
>
>  > Instead of backporting this patch [1] to kernel 4.19, select
>  > unconditionally the Kconfig option CONFIG_PPC_DISABLE_WERROR
>  > that allow to disable Werror.
>
>  > Fixes:
>  > https://gitlab.com/kubu93/toolchains-builder/-/jobs/205435741
>
>  > [1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=a6e60d84989fa0e91db7f236eda40453b0e44afa
>  > [2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=ba55bd74360ea4b8b95e73ed79474d37ff482b36
>  > [3] https://gitlab.com/bootlin/toolchains-builder
>
>  > Fix-suggested-by: Yann E. MORIN <yann.morin.1998@free.fr>
>  > Signed-off-by: Romain Naour <romain.naour@gmail.com>
>  > Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
>  > ---
>  > v2: add a shared fragment in board/fragments/linux and update
>  >     qemu ppc* defconfigs. (Arnout)
>
>  > v3: commit log (Yann)
>  >     enable the option from linux.mk instead of the defconfig.
>
> Committed to 2019.02.x and 2019.05.x, thanks.

It is in 2019.02.x, but not in 2019.05.x as of commit 1818dae1e0.

baruch

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