Re: Request to backport b3bee1e7c3f2b1b77182302c7b2131c804175870 (x86/boot: Compile boot code with -std=gnu11 too)

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, May 26, 2025 at 12:59:20PM +0200, Hendrik Donner wrote:
> Hello,
> 
> with gcc 15.1.1 i see the following build issue on 6.6.91:
> 
>   CC      arch/x86/boot/a20.o
> In file included from ./include/uapi/linux/posix_types.h:5,
>                  from ./include/uapi/linux/types.h:14,
>                  from ./include/linux/types.h:6,
>                  from arch/x86/boot/boot.h:22,
>                  from arch/x86/boot/a20.c:14:
> ./include/linux/stddef.h:11:9: error: cannot use keyword 'false' as
> enumeration constant
>    11 |         false   = 0,
>       |         ^~~~~
> ./include/linux/stddef.h:11:9: note: 'false' is a keyword with '-std=c23'
> onwards
> ./include/linux/types.h:35:33: error: 'bool' cannot be defined via 'typedef'
>    35 | typedef _Bool                   bool;
>       |                                 ^~~~
> ./include/linux/types.h:35:33: note: 'bool' is a keyword with '-std=c23'
> onwards
> ./include/linux/types.h:35:1: warning: useless type name in empty
> declaration
>    35 | typedef _Bool                   bool;
>       | ^~~~~~~
> make[2]: *** [scripts/Makefile.build:243: arch/x86/boot/a20.o] Error 1
> make[1]: *** [arch/x86/Makefile:284: bzImage] Error 2
> 
> Fixed by b3bee1e7c3f2b1b77182302c7b2131c804175870 (x86/boot: Compile boot
> code with -std=gnu11 too), which hasn't been backported yet.
> 
> Should probably go into all stable trees.z

Is this the only change that is needed to get gcc15 working on this
kernel tree?  What about newer kernel branches, they seem to be failing
on gcc15 still, which implies that 6.6.y still needs more changes,
right?

thanks,

greg k-h