2013-04-12 16:02:03

by Richard Weinberger

[permalink] [raw]
Subject: Re: [PATCH] x86: Default to ARCH=x86 to avoid overriding CONFIG_64BIT

David,

On Thu, Dec 20, 2012 at 10:51 PM, David Woodhouse <[email protected]> wrote:
> -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/ \

Why is this change needed? Especially the -e s/x86_64/x86.
It causes UML to get build for x86 which is a nasty change
of the default behavior.

Before your change you got a UML kernel for the underlying arch just
by running "make linux ARCH=um".
Now it will always build a x86 UML kernel, also if you run it on
x86_64 and one is forced to override
SUBARCH by hand.

--
Thanks,
//richard


2013-04-12 16:38:38

by David Woodhouse

[permalink] [raw]
Subject: Re: [PATCH] x86: Default to ARCH=x86 to avoid overriding CONFIG_64BIT

On Fri, 2013-04-12 at 18:01 +0200, richard -rw- weinberger wrote:
> David,
>
> On Thu, Dec 20, 2012 at 10:51 PM, David Woodhouse <[email protected]> wrote:
> > -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/ \
>
> Why is this change needed? Especially the -e s/x86_64/x86.
> It causes UML to get build for x86 which is a nasty change
> of the default behavior.

Which one? The "new" change of {i.86,x86_64} -> x86, or the pre-existing
ones for s390, parisc, powerpc and mips that it's falling into line
with?

> Before your change you got a UML kernel for the underlying arch just
> by running "make linux ARCH=um".
> Now it will always build a x86 UML kernel, also if you run it on
> x86_64 and one is forced to override
> SUBARCH by hand.

I know this was true a number of years ago when I first submitted this
fix. But I thought the ARCH=x86 UML build had been fixed since then. And
I was fairly sure I'd *tested* that belief when recently resubmitting...

Isn't it merely a case of setting CONFIG_64BIT to the desired value?

--
dwmw2


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