Re: problem with __init_cpu_features()

[The Source <thesourcehim at gmail dot com>]

19.05.2016 11:49, The Source ÐÐÑÐÑ:
> 19.05.2016 10:37, The Source ÐÐÑÐÑ:
> > 18.05.2016 21:53, Carlos O'Donell ÐÐÑÐÑ:
> > > 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.