[arch-dev-public] x86_64: improving default CFLAGS
ganja.guru.x64 at gmail.com
Wed Apr 4 21:01:34 EDT 2007
Roman Kyrylych wrote:
> 2007/4/4, Andreas Radke <a.radke at arcor.de>:
>> Am Tue, 3 Apr 2007 16:40:20 -0500
>> schrieb "Aaron Griffin" <aaronmgriffin at gmail.com>:
>>>>> to not break backward compatibility for those few early cpus that
>>>>> lack SSE3 extensions we want to do it with -mtune. this is how we
>>>>> want to set it for the future:
>>>>> CFLAGS="-march=x86-64 -mtune=nocona -O2 -pipe"
>>>>> CXXFLAGS="-march=x86-64 -mtune=nocona -O2 -pipe"
>>> I don't know the details, so I assumed you looked into it all. Just
>>> in case: what 64bit processors does this "leave in the dust".
>>> Dropping support for some processors is not a huge problem (the age
>>> old Via C3 + Arch problem), but i think it might be important to put a
>>> blurb somewhere saying "If you have an XYZ processor, you need to use
>>> the arch i686".
>> i don't want to drop support for any early x86_64 cpu.
>> that's why i want to use "mtune". code will be optimized for SSE3
>> capable cpus but will still run on non SSE3 capable processors. that's
>> the difference mtune to march.
>> i686 had something similar prepared in the old makepkg.conf
>> i don't expect a big gain at all but in certain multimedia apps it can
>> speedup things a lot. so why not make use of the additional registers?
>> apps *might* run a little bit slower if they cannot make use of the
>> additional flags and will it probably raise the pkg size a bit. but it
>> should be still worth it.
> I don't mind mtune (I've read forum thread).
I don't mind mtune either, as long as I (and others with similar
hardware - non SSE3 ) don't take any hit from the change .
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