Re: [PATCH v3] x86, kconfig: Default to ARCH=x86 to avoid overriding CONFIG_64BIT

From: Arnaud Lacombe
Date: Sat Jul 30 2011 - 11:52:22 EST


Hi,

On Fri, Jul 29, 2011 at 8:49 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> I *frequently* waste a bunch of time when I take a 32-bit .config from a
> test machine and try to build it on a faster 64-bit system, and its
> existing setting of CONFIG_64BIT=n gets *changed* to match the build host.
>
> This is because the default setting for $ARCH when discovered from
> 'uname' is one of the legacy pre-x86-merge values (i386 or x86_64),
> which effectively force the setting of CONFIG_64BIT to match. We should
> default to ARCH=x86 instead, finally completing the merge that we
> started so long ago.
>
> This patch preserves the behaviour of the legacy ARCH settings for commands
> such as:
>
>   make ARCH=x86_64 randconfig
>   make ARCH=i386 randconfig
>
> ... although since my commit "Enable 'make CONFIG_FOO=y oldconfig'" those
> would be better expressed as:
>
>   make CONFIG_64BIT=y randconfig
>   make CONFIG_64BIT=n randconfig
>
> ... since that is a more generic way to set *any* config option, and
> there's no other technical reason to keep the legacy ARCH values around
> any more just to achieve that purpose; they could be removed at any
> time.
>
> Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
> Link: http://lkml.kernel.org/r/1306707270.2029.377.camel@xxxxxxxxxxxxxxxx
> ---
> v2: Explicitly turn off CONFIG_64BIT in i386_defconfig. The default for
>    CONFIG_64BIT has *changed* (from n to y) for ARCH=x86, so it needs to
>    be explicitly turned off or 'make i386_defconfig' will give you 64-bit.
> v3: Same patch as before; just updated changelog.
>
>  Makefile                        |    3 ++-
>  arch/x86/Kconfig                |    2 +-
>  arch/x86/Makefile               |    4 ++++
>  arch/x86/configs/i386_defconfig |    1 +
>  4 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index d018956..303df9b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -165,7 +165,8 @@ export srctree objtree VPATH
>  # then ARCH is assigned, getting whatever value it gets normally, and
>  # SUBARCH is subsequently ignored.
>
> -SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
> +SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
> +                                 -e s/sun4u/sparc64/ \
>                                  -e s/arm.*/arm/ -e s/sa110/arm/ \
>                                  -e s/s390x/s390/ -e s/parisc64/parisc/ \
>                                  -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
this is breaking ARCH=um.

- Arnaud
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