# Atom N270 shows one CPU

## njcwotx

I am fresh building a system with an Atom N270 processor.

I recall the live cd showed 2 cpus.  I 'thought' i had 2 cpus when I first built the kernel, but I could be wrong.

SMP and SMT (hyperthread) are enabled, processor type is listed as 'Atom' in menuconfig.

I am assuming I have a problem in the kernel setup but it looks ok to me.  I did have wrong arch set I think, it was 'i686' now I changed it to 'native' did a 'make clean' and in the process of recompiling the kernel.

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## xibo

The Atom N270 has only one core. If your live-cd showed a second one it's the hyperthreading fake. You can check the number of maximal CPUs in the same page of make menuconfig where you can enable hyperthreading scheduling and you might also want to check your bios settings for HT.Last edited by xibo on Fri Aug 06, 2010 5:37 pm; edited 1 time in total

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## njcwotx

changing arch to native gave no change in CPU

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## eccerr0r

If the livecd really shows 2 CPUs, and you have multiprocessor and HT support enabled, how about ACPI enabled in your kernel?

Are you editing your .config or using make menuconfig/make config/make xconfig?

-arch=native shouldn't matter...

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## njcwotx

i did not have acpi enabled, but I am actually building one now with it enabled.

I use 'make menuconfig to set values, but I will comb through config to double check from time to time.

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## naelq

the Atom N270 is a Dual Threaded Single Core CPU. http://ark.intel.com/Product.aspx?id=36331

could you please post the output of:

```
zcat /proc/config.gz | grep -i cpu
```

or, in case you did not include the .config within the kernel:

```
cat /usr/src/linux/.config | grep -i cpu
```

nael

[edit]typos, POS keyboard![/edit]

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## njcwotx

I did check the live CD and it showed 2. 

I knew it was a hyperthreading fake, however that still show show up the same as my other boxes that use it.

im going to try this new build with acpi and will post with configs if that does not work.

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## njcwotx

adding power management support 'SUPPORT_PM' (which includes ACPI) did the trick, I see it now.

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## eccerr0r

ACPI gets MT/SMP people again and again.

It's not the Power Interface of ACPI, it's the Configuration of ACPI.

Add [Solved] to the title when you think it's all good!

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