linux-kernel - Re: arch/arm/boot/compressed/fdt_check_mem_start.c:62:10: warning: no previous prototype for function 'fdt_check_mem

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Message-ID: <CAMuHMdXUpk_dLhvcdgs1H6yLPrwXFJz_86dfXpm8PYxNq+DXrQ@mail.gmail.com>
Date:   Sat, 21 Aug 2021 10:45:57 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     kernel test robot <lkp@...el.com>
Cc:     clang-built-linux <clang-built-linux@...glegroups.com>,
        kbuild-all@...ts.01.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: Re: arch/arm/boot/compressed/fdt_check_mem_start.c:62:10: warning: no
 previous prototype for function 'fdt_check_mem_start'

Dear Robot,

On Sat, Aug 14, 2021 at 7:43 AM kernel test robot <lkp@...el.com> wrote:
> FYI, the error/warning still remains.

Yes, and that's fine, as this function is never called from C code,
only from assembler.

> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   dfa377c35d70c31139b1274ec49f87d380996c42
> commit: 0673cb38951215060d7993b43ad3c45cd413c2c3 ARM: 9045/1: uncompress: Validate start of physical memory against passed DTB
> date:   6 months ago
> config: arm-randconfig-r003-20210814 (attached as .config)
> compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 62df4df41c939205b2dc0a2a3bfb75b8c1ed74fa)
> reproduce (this is a W=1 build):
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0673cb38951215060d7993b43ad3c45cd413c2c3
>         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>         git fetch --no-tags linus master
>         git checkout 0673cb38951215060d7993b43ad3c45cd413c2c3
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
>
> All warnings (new ones prefixed by >>):
>
> >> arch/arm/boot/compressed/fdt_check_mem_start.c:62:10: warning: no previous prototype for function 'fdt_check_mem_start' [-Wmissing-prototypes]
>    uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
>             ^
>    arch/arm/boot/compressed/fdt_check_mem_start.c:62:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
>    uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
>    ^
>    static
>    1 warning generated.
>
>
> vim +/fdt_check_mem_start +62 arch/arm/boot/compressed/fdt_check_mem_start.c
>
>     46
>     47  /*
>     48   * Check the start of physical memory
>     49   *
>     50   * Traditionally, the start address of physical memory is obtained by masking
>     51   * the program counter.  However, this does require that this address is a
>     52   * multiple of 128 MiB, precluding booting Linux on platforms where this
>     53   * requirement is not fulfilled.
>     54   * Hence validate the calculated address against the memory information in the
>     55   * DTB, and, if out-of-range, replace it by the real start address.
>     56   * To preserve backwards compatibility (systems reserving a block of memory
>     57   * at the start of physical memory, kdump, ...), the traditional method is
>     58   * always used if it yields a valid address.
>     59   *
>     60   * Return value: start address of physical memory to use
>     61   */
>   > 62  uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt)
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org



-- 
Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds