Re: Yocto development with C++11 threads and gcc

["Peter A. Bigot" <pab@pabigot.com>]

On 08/13/2014 04:18 PM, Khem Raj wrote:
> On Mon, Aug 11, 2014 at 12:02 PM, Peter A. Bigot <pab@pabigot.com> wrote:
>> The program below built on the target with the MACHINE=beaglebone gcc-4.9.1
>> compiler from Yocto/OpenEmbedded poky master produces this error:
>>
>> beaglebone[52]$ g++ -std=c++1y -pthread test.cc && ./a.out
>> starting
>> joining
>> pure virtual method called
>> terminate called without an active exception
>> Aborted (core dumped)
>>
>> When the program is recompiled with the defines for
>> __GCC_HAVE_SYNC_COMPARE_AND_SWAP_X enabled as suggested at
>> https://groups.google.com/d/msg/automatak-dnp3/Jisp_zGhd5I/ck_Cj6nO8joJ it
>> works:
>>
>> beaglebone[53]$ g++ -std=c++1y -pthread test.cc && ./a.out
>> starting
>> joining
>> doit
>> done
>>
>> Preliminary analysis confirms that the built-ins for those defines are not
>> being added by the compiler because it thinks the target doesn't support
>> those operations.  Nonetheless, it doesn't use the substitutes that are
>> obviously available.
>>
>> Can anybody recall anything about the way GCC is built under OE that would
>> explain this?
> Can you add -mcpu=cortex-a8 to your cmdline and see if it solves the problem ?

Yes, it does.  That's a good clue.

Peter

>> Peter
>>
>> /* g++ -std=c++1y -pthread test.cc && ./a.out */
>> #if 0
>> #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1
>> #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2
>> #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
>> #define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8
>> #endif
>>
>> #include <iostream>
>> #include <thread>
>>
>> void
>> doit ()
>> {
>>    std::cerr << "doit\n";
>> }
>>
>> int main (int argc,
>>            char * argv [])
>> {
>>    std::cerr << "starting\n";
>>    std::thread thr{doit};
>>    std::cerr << "joining\n";
>>    thr.join();
>>    std::cerr << "done\n";
>>    return 0;
>> }
>>
>> --
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