# Run a Gentoo compiled for AMD Athlon XP on Athlon 64 X2?

## justXi

Hi,

I currently using an Athlon XP, but I need to change my mainboard and I am thinking about to buy an Athlon 64 X2. 

Can I use my Gentoo system compiled for Athlon XP on an Athlon 64 without changes?

Which cpu would I select for the kernel, Athlon or Athlon 64? 

Or is it possible to simply switch on SMP and run for now in 32 bit mode?

Thanks for information =).

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## Monkeh

No changes required, just adjust the kernel to handle the new hardware and you'll be good to go.

It'd be a good idea to adjust your CFLAGS to suit (just let new programs and upgrades use them, no need for a rebuild), and enable suitable USE flags (like sse2).

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## justXi

But when I compile the kernel for AMD 64 I have to compile the system for AMD64, too?

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## cyrillic

The kernel that you compile will still be 32bit, unless you have a 64bit compiler installed that you didn't mention before.

ps.  The reason for compiling a new kernel is to support your new PATA/SATA controller(s), onboard ethernet, onboard audio, etc.  The CPU itself will work fine without modifying the kernel.

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## justXi

Ok, thanks for the information.

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## johnisevil

I'd recommend doing a kernel recompile anyways so you can enable SMP to make use of the second core your X2 CPU will have.

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