Re: [PATCH] powerpc: clean vdso32 and vdso64 directories

From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Masahiro Yamada <masahiroy@kernel.org>, linux-kernel@vger.kernel.org
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	linuxppc-dev@lists.ozlabs.org,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH] powerpc: clean vdso32 and vdso64 directories
Date: Tue, 16 Nov 2021 16:37:58 +0100	[thread overview]
Message-ID: <0cdd39b2-73f8-e0c1-bfa2-7940d4b788f0@csgroup.eu> (raw)
In-Reply-To: <20211109185015.615517-1-masahiroy@kernel.org>

Hi Masahiro,

Le 09/11/2021 à 19:50, Masahiro Yamada a écrit :
> Since commit bce74491c300 ("powerpc/vdso: fix unnecessary rebuilds of
> vgettimeofday.o"), "make ARCH=powerpc clean" does not clean up the
> arch/powerpc/kernel/{vdso32,vdso64} directories.
> 
> Use the subdir- trick to let "make clean" descend into them.
> 
> Fixes: bce74491c300 ("powerpc/vdso: fix unnecessary rebuilds of vgettimeofday.o")
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>   arch/powerpc/kernel/Makefile | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 0e3640e14eb1..5fa68c2ef1f8 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -196,3 +196,6 @@ clean-files := vmlinux.lds
>   # Force dependency (incbin is bad)
>   $(obj)/vdso32_wrapper.o : $(obj)/vdso32/vdso32.so.dbg
>   $(obj)/vdso64_wrapper.o : $(obj)/vdso64/vdso64.so.dbg
> +
> +# for cleaning
> +subdir- += vdso32 vdso64
> 

This patch make me think about one thing I would have liked to do, but I 
don't know Makefiles well enough to be able to do it. You could probably 
help me with it.

vdso32 and vdso64 contain a lot of redundant sources. I would like to 
merge them into a new single directory, let say 'vdso', and use the 
files in that directory to build both vdso32.so and vdso64.so. I have a 
feeling that x86 is doing it that way, but I've not been able to figure 
out how to build two objects using the same C/S files.

Thanks
Christophe