Recent fixes have been backported to < v5.18 to fix build issues with
GCC 5.15. They all force -std=gnu11 in the CFLAGS, "because [the kernel]
requests the gnu11 standard via '-std=' in the main Makefile".
This is true for >= 5.18 versions, but not before. This switch to
-std=gnu11 has been done in commit e8c07082a8 ("Kbuild: move to
-std=gnu11").
For a question of uniformity, force -std=gnu89, similar to what is done
in the main Makefile.
Note: the fixes tags below refers to upstream commits, but this fix is
only for kernels not having commit e8c07082a8 ("Kbuild: move to
-std=gnu11").
Fixes: 7cbb015e2d ("parisc: fix building with gcc-15")
Fixes: 3b8b80e993 ("s390: Add '-std=gnu11' to decompressor and purgatory CFLAGS")
Fixes: b3bee1e7c3 ("x86/boot: Compile boot code with -std=gnu11 too")
Fixes: ee2ab467bd ("x86/boot: Use '-std=gnu11' to fix build with GCC 15")
Fixes: 8ba14d9f49 ("efi: libstub: Use '-std=gnu11' to fix build with GCC 15")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
518eadd15f