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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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.  It is more important to reduce divergence from upstream Kconfig.

After all, x86_128 is likely to come along sometime.

~Andrew

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