Bug#792204: Setting default CPU to ultrasparc for -m32 on sparc64 does not work
On 07/20/2015 12:31 PM, Matthias Klose wrote:
> On 07/20/2015 01:37 AM, Michael Karcher wrote:
>> Hello,
>>
>> the problem (ATOMIC_INT_LOCK_FREE == 1) applies for the 32-bit build of
>> libstdc++,
>> and is caused by gcc assuming a too old 32-bit sparc processor, as can
>> be seen by:
>>
>>> (unstable-sparc64-sbuild)mkarcher@ravirin:~$ COLUMNS=140 dpkg -l gcc-4.9
>>> Desired=Unknown/Install/Remove/Purge/Hold
>>> |
>> Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
>>> |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
>>> ||/ Name Version
>> Architecture Description
>>>
>> +++-=============================-===================-===================-===============================================================
>>> ii gcc-4.9 4.9.2-21+sparc64
>> sparc64 GNU C compiler
>>
>> (this is a custom build of the official debian gcc source with the
>> symbol verification
>> quieted by using fudged expected symbols lists)
>>
>>> (unstable-sparc64-sbuild)mkarcher@ravirin:~$ g++-4.9 -std=c++11 -dM -E
>> -m32 -x c++ /dev/null | grep INT_LOCK
>>> #define __GCC_ATOMIC_INT_LOCK_FREE 1
>>> (unstable-sparc64-sbuild)mkarcher@ravirin:~$ g++-4.9 -std=c++11 -dM -E
>> -m32 -mcpu=ultrasparc -x c++ /dev/null | grep INT_LOCK
>>> #define __GCC_ATOMIC_INT_LOCK_FREE 2
>>
>> The changelog messages for gcc seem to indicate that the default CPU for
>> -m32 is
>> intended to be ultrasparc:
>>
>>> gcc-4.9 (4.9.0-10) unstable; urgency=medium
>>>
>>> * Update to SVN 20140704 (r212295) from the gcc-4_9-branch.
>>>
>>> * Explicitly set cpu_32 to ultrasparc for sparc64 builds.
>> [...]
>>> gcc-4.9 (4.9.0-9) unstable; urgency=medium
>>>
>>> * Update to SVN 20140701 (r212192) from the gcc-4_9-branch.
>>> * Update libstdc++ symbols files for ARM.
>>> * Configure --with-cpu-32=ultrasparc on sparc64.
>>
>> This seems to not have the intended effect of defaulting to require the
>> ultrasparc
>> architecture providing lock-free atomics.
>>
>> Regards,
>> Michael Karcher
>
> see sparc-force-cpu.diff, which currently disables this for sparc64 biarch. So
> maybe somebody should just enable it and see if it works as intended, or make it
> working.
ahh, and r7502 disabled it again, so probably somebody should have a look how to
set the default for the 32bit build.
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