[Buildroot] Fail to compile Linux kernel 5.14 with GCC15

[Buildroot] Fail to compile Linux kernel 5.14 with GCC15

[David Luca via buildroot]

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Hello, 
As mentioned in the title, I receive a compile error for arch/x86/realmode/rm/wakemain.c:
./include/linux/stddef:11:9: error: cannot use keyword 'false' as enumeration constant
Note: 'false'is a keyword with' '-std=c23' onwards. 
So I patched my buildroot linux/linux.mk to add:
ifeq ($(BR_TOOLCHAIN_GCC_AT_LEAST_15),y)
LINUX_CFLAGS += -std=gnu17
endif
However the compiler error is still happening, any idea how to fix? 
Best regards, 
David. 

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Re: [Buildroot] Fail to compile Linux kernel 5.14 with GCC15

[Julien Olivain via buildroot]

Hi David,

On 13/11/2026 11:14, David Luca via buildroot wrote:
> Hello,
> As mentioned in the title, I receive a compile error for
> arch/x86/realmode/rm/wakemain.c:
> ./include/linux/stddef:11:9: error: cannot use keyword 'false' as
> enumeration constant
> Note: 'false'is a keyword with' '-std=c23' onwards.
> So I patched my buildroot linux/linux.mk to add:
> ifeq ($(BR_TOOLCHAIN_GCC_AT_LEAST_15),y)
> LINUX_CFLAGS += -std=gnu17
> endif
> However the compiler error is still happening, any idea how to fix?

Kernel 5.14 was not a LTS, you should consider updating
your kernel. If not possible, you could probably backport
fixes from 5.15, such as:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f28b14d235a810e4f6634832062b6e0ffc482b5a
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=518eadd15f7ecde6d301974388c6be03d5c57a0c
...

You can probably search relevant commits with:
git log -S std= linux-5.15.y

> Best regards,
> David.

Best regards,

Julien.
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