Re: [Xen-devel] [PATCHv6] 02/28] build: build Kconfig and config rules

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2015-12-08 at 18:04 +0000, Andrew Cooper wrote:
> On 08/12/15 17:59, Doug Goldstein wrote:
> > On 12/8/15 8:25 AM, Jan Beulich wrote:
> > > > > > On 08.12.15 at 15:16, <cardoe@xxxxxxxxxx> wrote:
> > > > On 12/8/15 1:32 AM, Jan Beulich wrote:
> > > > > > > > On 07.12.15 at 22:27, <cardoe@xxxxxxxxxx> wrote:
> > > > > > On 12/3/15 2:57 AM, Jan Beulich wrote:
> > > > > > > > > > On 03.12.15 at 01:34, <cardoe@xxxxxxxxxx> wrote:
> > > > > > > > On 12/1/15 5:22 AM, Jan Beulich wrote:
> > > > > > > > > > > > On 30.11.15 at 18:53, <cardoe@xxxxxxxxxx> wrote:
> > > > > > > > > > On 11/30/15 8:36 AM, Jan Beulich wrote:
> > > > > > > > > > > > > > On 24.11.15 at 18:51, <cardoe@xxxxxxxxxx>
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > +config ARCH_DEFCONFIG
> > > > > > > > > > > > +       string
> > > > > > > > > > > > +       default
> > > > > > > > > > > > "arch/x86/configs/x86_64_defconfig"
> > > > > > > > > > > x86_defconfig perhaps?
> > > > > > > > > > No. I was told to drop support for x86 entirely in an
> > > > > > > > > > earlier review.
> > > > > > > > > > Its not possible to configure for 32-bit x86 in v6.
> > > > > > > > > x86 != 32-bit. I think you're mixing this up with ix86 or
> > > > > > > > > x86-32.
> > > > > > > > > Here I consider x86 as to basic architecture without any
> > > > > > > > > particular bit width in mind.
> > > > > > > > ok. Well the syntax is still
> > > > > > > > "arch/SUBARCH/configs/ARCH_defconfig" so
> > > > > > > > the original is correct. There is no defconfig for the
> > > > > > > > ambiguous x86
> > > > > > > > family. You're either building for x86_64 or x86_32 (which
> > > > > > > > I referred to
> > > > > > > > as x86 in my original response).
> > > > > > > > 
> > > > > > > > This defconfig is for the 64-bit architecture of x86
> > > > > > > > (x86_64) and there
> > > > > > > > for its named correctly.
> > > > > > > But there is no x86_32 architecture form the hypervisor
> > > > > > > build's
> > > > > > > point of view, and hence x86 isn't ambiguous. In fact the
> > > > > > > mid-term
> > > > > > > plan is to remove leftovers of references to x86_64 (like the
> > > > > > > arch/x86/x86_64/ or include/asm-x86/x86_64/ directories)
> > > > > > > where
> > > > > > > possible. The only place they need to be kept are in the
> > > > > > > public
> > > > > > > interface.
> > > > > > That's fine but you don't build things for "x86". You build
> > > > > > them for
> > > > > > "x86_64". XEN_TARGET_ARCH takes in "x86_64".
> > > > > The XEN_TARGET_ARCH value is of no interest here. The only fact
> > > > > that I care about is that there's only one x86 configuration, and
> > > > > hence I can't see why it shouldn't be named x86_defconfig.
> > > > This is just how the upstream stuff works. Are we forking
> > > > upstream's
> > > > kconfig just so we can call it "x86" instead of "x86_64"?
> > > I don't think using
> > > 
> > > config ARCH_DEFCONFIG
> > >   string
> > >   default "arch/x86/configs/x86_defconfig"
> > > 
> > > instead of
> > > 
> > > config ARCH_DEFCONFIG
> > >   string
> > >   default "arch/x86/configs/x86_64_defconfig"
> > > 
> > > in a Kconfig file of ours is a fork. Or am I overlooking some other
> > > aspect?
> > > 
> > > Jan
> > > 
> > Its not that simple. When you run "make defconfig" it will default to
> > using "arch/$(SRCARCH)/configs/$(ARCH)_defconfig". Where SRCARCH =
> > TARGET_ARCH and ARCH = TARGET_SUBARCH = XEN_TARGET_ARCH. So to use real
> > values from the documentation how to build Xen:
> > 
> > - XEN_TARGET_ARCH=x86_64 make defconfig
> > - XEN_TARGET_ARCH=arm32 make defconfig
> > - XEN_TARGET_ARCH=arm64 make defconfig
> > 
> > The result is things build correctly. To make the variable build ups
> > change for x86 vs arm would require us to fork
> > xen/tools/kconfig/Makefile line 101 (potentially others).
> 
> Frankly, I don't think it is worth worrying that x86_64 could be
> shortened.ÂÂIt is more important to reduce divergence from upstream
> Kconfig.

Agreed.

> After all, x86_128 is likely to come along sometime.

You owe me a new keyboard and a new cup of coffee.

Ian.

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