# core2duo make.conf

## Crooksey

As gentoo wiki is down my refrence for re-installs has gone, could anyone share their make.conf for their core2duo system, mainly just the CFLAGS, thanks.

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## zyko

This is mine, for gcc-4.3.1. It's the same for x86 and amd64:

```
CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"

CXXFLAGS="${CFLAGS}"

MAKEOPTS="-j3"
```

The currently stable GCC-4.1.2 doesn't support -march=native. The next best thing is -march=prescott (for x86) or -march=nocona (for amd64).

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## d2_racing

Hi, i use this with my Quad Core :

```

CFLAGS="-O2 -march=nocona -pipe"

CHOST="x86_64-pc-linux-gnu"

CXXFLAGS="${CFLAGS}"

MAKEOPTS="-j5"

```

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## desultory

You could use the snapshot cached by Google.

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## Crooksey

Thanks, much appreciated.

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## Paapaa

 *zyko wrote:*   

> This is mine, for gcc-4.3.1. It's the same for x86 and amd64:
> 
> ```
> CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"
> 
> ...

 

"-fomit-frame-pointer" is always on by default with "-O2" (and with -O1, -O3, -Os) when it doesn't interfere debugging. This includes all x86_64 setups.

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## d2_racing

Also, there a lot of thing that are include inside -O2 :

http://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Optimize-Options.html

http://gcc.gnu.org/onlinedocs/gcc-4.3.2/gcc/i386-and-x86_002d64-Options.html

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## pilla

There's a new option, -march=core2, that I wasn't aware.

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## d2_racing

In fact, -march=core2 is the best option, because if you use native, the Gcc has to compare his database to see what Gcc option that he will use.

Specifying the right arch, this will safe a split second on every package.

The puriste use the right arch and they not let Gcc figure this out my himself.

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## Schwinni

Basically you are right, but there are some packages which don't compile with gcc 4.3.x, e.g. pdftk.

For that you need gcc 4.2.x, which doesn't understand -march=core2.

But gcc 4.2 supports march=native.

This way you don't have to change your make.conf every time you switch your gcc for a certain package.

The optimization result should be the same anyway...

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