Re: Kconfig: ARCH=x86 causes wrong utsname.machine

H. Peter Anvin
2007-11-16T22:59:00Z

Sam Ravnborg wrote:
> On Fri, Nov 16, 2007 at 07:20:15AM -0800, H. Peter Anvin wrote:
>> Andreas Herrmann wrote:
>>> The new ARCH=x86 kernel build causes weired machine strings on 32-bit.
>>> For a cross-compiled kernel I have
>>>
>>> $ uname -m
>>> x66_64
>>>
>>> For a kernel natively built on a 32 bit machine I have
>>>
>>> $ uname -m
>>> x66
>>>
>>> Looking at the sources, I think that utsname->machine was initially
>>> set as "x86_64" and "x86", respectively.
>>> But in arch/x86/kernel/cpu/bugs.c in check_bugs() the second character
>>> is set to '6' on my K7.
>>>
>>> I think the right solution for that problem is to use "x86_64" as the
>>> machine name for 64-bit and to keep the old "i[3456]86" strings for
>>> 32-bit kernels.
>> Absolutely. This would be userspace-visible ABI breakage.
>
> Any good suggestions here???
> UTS_MACHINE is set in top-level Makefile and if we specify
> make ARCH=x86
> we do not know if i386 or x86_&4 is correct until the configuration
> has been read.
>
> Should we report a "make ARCH=x86" as uname -m == x86??
>

That would break 5 years of a stable ABI. I don't think that is even
remotely feasible.

-hpa