Discussion: What processor type (family) to select for Intel Atom in Linux kernel config
So I am excited to start a new type of post, “Discussion” besides the regular INFO, HOWTO, TIP, etc. The purpose of such type of post is to generate a discussion regarding certain issues for which there is a no clear answers in the Linux community. In my past 4 years of Linux usage, I have come across a variety of such issues and today I would like to start with one of them.
Question: What “Processor Family” to select under “Processor types and features” in the Linux kernel for the latest Intel Atom processor machines?
Now there are few variants of the Atom processor. I am specifically talking about the “Intel Z5XX” type processors which are being found in the now discontinued Dell Mini 12. Now these processors are not actually dual core based but they do have some kind of hyper-threading which makes modern Operating Systems to think that it is a dual core processor. However in reality and technically they are not. So how do we (Linux users) do in this case? Should be select the Core 2 option as shown below:
Dual Core Linux kenrel
or the standard 585/686/686MX option as shown below:
Linux 686 processor type
or should there be a separate option like, “Intel Atom” in the Linux kernel processor types?
If you select either one of them, the system will boot fine but we are not sure what is the optimum option. Usually these options are selected based on the processor flags that your CPU supports. You can see what flags your processor supports by the following command:
# cat /proc/cpuinfo | grep flags
Here is an interesting discussion on the LKML regarding this issue. And here is another one (less technical).
Lastly I would like to know from people who have purchased Atom-based netbooks and nettops which ships with a Linux distribution, what “Processor Family” came selected by default? Personally, I am using the “Dual Core” option on my Atom-based system.
The post is open for comments. So share your experience.What “Processor Family” to select under “Processor types and features” in the Linux kernel for the latest Intel Atom processor machines.
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December 11th, 2009 at 3:39 am
In the new 2.6.32 kernel there is a support for atom processor…or Do I wrong?
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March 1st, 2010 at 10:56 am
According the the product data sheets at Intel the Z5XX and N2XX processors do not support 64-bit instructions so the i686 is the correct choice. The product sheets are here: http://ark.intel.com/ProductCollection.aspx?familyID=29035
The newer Atom D410 and D510 will support 64-bit instructions. So you could probably use the amd64 distro for those processos. My N270 shows up as dual-core on Debian 5.0(Squeeze).
There probably won’t be a special configuration for the Atom until GCC supports it. GCC 4.5 has options for the Intel Atom as listed on the Gentoo Linux wiki here: http://en.gentoo-wiki.com/wiki/Safe_Cflags/Intel#Atom_N270.2FN280
Maybe after gcc 4.5 ships there will be a new build option for the linux kernel?
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