Am 11.06.2011 17:25, schrieb Jarry: > Hi, > how should I change/set CFLAGS/CXXFLAGS/CHOST if I want to have > system which can be easily migrated between AMD64 and Intel/Core > without recompilation? I have a few virtual servers which I can > not move from one arch to the other, as they have hw-specific > CFLAGS (different host-server hardware, both AMD64 and EM64T): > > I have systems with Athlon64/X2 and Core2Quad, with settings: > CFLAGS="-march=athlon64 -O2 -pipe" > CFLAGS="-march=core2 -O2 -pipe" > CHOST is always "x86_64-pc-linux-gnu". > > I'm not sure "-mtune=generic" is the right solution, because > it would generate code for IA32/AMD64/EM64T (if I understand > gcc manual correctly, for both 32bit as well as 64bit HW). > > What I'm looking for are some generic 64bit settings only for > AMD64/EM64T (not 32bit/IA32) similar as for distros with binary > distributions (i.e. I can download Ubuntu either 32bit or 64bit > version, no other hardware-specific difference). I know with > "universal" 64bit binaries I'm going to loose some pefrormance, > but for me flexibility with migration would overweight this > disadvantage... > > Jarry >
Unless you specify -m32, your x86_64 gcc will create generic x86_64 code. That means it will use the common AMD64/EM64T instruction set which also includes SSE2 instructions. Regards, Florian Philipp
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