Re: problem with __init_cpu_features()

[The Source <thesourcehim@gmail.com>]

19.05.2016 11:49, The Source пишет:
> 19.05.2016 10:37, The Source пишет:
>> 18.05.2016 21:53, Carlos O'Donell пишет:
>>> On Wed, May 18, 2016 at 10:55 AM, Carlos O'Donell
>>> <carlos@systemhalted.org> wrote:
>>>> On Wed, May 18, 2016 at 10:37 AM, The Source 
>>>> <thesourcehim@gmail.com> wrote:
>>>>> Hello, I'm trying to run my application on Cyrix Cx486SLC based 
>>>>> system. But
>>>>> application (built for i486 as well as glibc) crashes on illegal 
>>>>> instruction
>>>>> inside __init_cpu_features(). As far as I understand this CPU does 
>>>>> not
>>>>> support cpuid (/proc/cpuinfo reports cpuid level -1 and 
>>>>> /dev/cpu/0/cpuid can
>>>>> not be read with i/o error), so that might be the problem. Is 
>>>>> there a way to
>>>>> avoid using __cpuid()? My glibc version is 2.22
>>>> You must use specific CFLAGS or CC to indicate you are building for a
>>>> pre-i586 target, that will disable unconditional cpuid usage, and
>>>> enable the checks required to verify cpuid is usable.
>>>>
>>>> If you are cross-compiling from an x86_64 box I would recommend
>>>> CC="gcc -m32 -march=i486" instead to ensure that regardless of flags
>>>> you build for i486.
>>>>
>>>> Just to check I kicked off a build for i486 locally to see if runs
>>>> into any problems.
>>> i486 builds just fine and I verified it calls __get_cpuid_max to check
>>> for cpuid feature.
>>>
>>> Test results look good too.
>>>
>>> Cheers,
>>> Carlos.
>>
>> Unfortunately, adding those flags to compiler for both libc and 
>> application did not help. I found out that __init_cpu_features is 
>> located inside libpthread somehow. So my application crashes when it 
>> uses threads. Could there be some unwanted optimization inside pthread?
>>
> Hmm, I see some strange things in glibc config.log. It appears that 
> some subconfigs are called with i686 despite main script is called 
> with --with-cpu=i486. Trying to figure out if it's configure bug or 
> crosstools-ng.
>
>
I'm out of ideas. I tried to restrict gcc from building anything but 
i486 (by passing the following flags to configure of both gcc and glibc: 
--with-cpu=i486 --with-cpu-32=i486 --with-arch=i486 --with-arch-32=i486 
--enable-targets=i486), but it did not help, I still see those i686 
successful tests in config.log and libpthread still has 
__init_cpu_features. If anyone have any idea how to forbid i686, I'm 
open for suggestions, thank you.



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