Re: linux-next: build failure after merge of the kbuild tree

From: Masahiro Yamada <masahiroy@kernel.org>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Next Mailing List <linux-next@vger.kernel.org>
Subject: Re: linux-next: build failure after merge of the kbuild tree
Date: Fri, 14 Oct 2022 22:31:59 +0900	[thread overview]
Message-ID: <CAK7LNARg8OpqLR_71PJV3ZoLuDV8+mz9mphg=CzEeEEMY0G3rw@mail.gmail.com> (raw)
In-Reply-To: <20221014124217.20fd0a27@canb.auug.org.au>

On Fri, Oct 14, 2022 at 10:42 AM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi all,
>
> After merging the kbuild tree, today's linux-next build (i386 defconfig)
> failed like this:
>
> In file included from arch/x86/kernel/head_32.S:29:
> arch/x86/include/asm/pgtable_32.h:68:5: error: "PTRS_PER_PMD" is not defined, evaluates to 0 [-Werror=undef]
>    68 | #if PTRS_PER_PMD > 1
>       |     ^~~~~~~~~~~~
> cc1: all warnings being treated as errors
>
> Exposed by commit
>
>   0a7606a9832a ("kbuild: move -Wundef from KBUILD_CFLAGS to KBUILD_CPPFLAGS")
>
> I have no idea what the root cause is. :-(
>
> It is a great pity that this commit was not in linux-next before the
> merge window opened. :-(

Sorry for the annoyance again.

I gave up this patch for now.

I will drop it and need to sort out warnings.

>
> I have applied the following hack for today.
>
> From: Stephen Rothwell <sfr@canb.auug.org.au>
> Date: Fri, 14 Oct 2022 12:34:34 +1100
> Subject: [PATCH] i386: hack for "kbuild: move -Wundef from KBUILD_CFLAGS to KBUILD_CPPFLAGS"
>
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  arch/x86/include/asm/pgtable_32.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/pgtable_32.h b/arch/x86/include/asm/pgtable_32.h
> index 7c9c968a42ef..0f3f186ca140 100644
> --- a/arch/x86/include/asm/pgtable_32.h
> +++ b/arch/x86/include/asm/pgtable_32.h
> @@ -65,7 +65,7 @@ do {                                          \
>   * With PAE paging (PTRS_PER_PMD > 1), we allocate PTRS_PER_PGD == 4 pages for
>   * the PMD's in addition to the pages required for the last level pagetables.
>   */
> -#if PTRS_PER_PMD > 1
> +#if defined(PTRS_PER_PMD) && (PTRS_PER_PMD > 1)
>  #define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
>  #else
>  #define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
> --
> 2.35.1
>
> --
> Cheers,
> Stephen Rothwell

-- 
Best Regards
Masahiro Yamada