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.
Regards, Hendrik