Kernel not detect all core of cpu's
 

Hi
We have compiled kernel 2.6.30 from source code.But this kernel can not detect all core of cpu's.
on our system there are 2 cpu's and every cpu has 2 cores.but in /proc/cpuinfo there are 2 cpu's and every cpu has one core!!
I could not solve this problem yet.

Thanks for any help or guidance

Hi,

You might want to set one or both of these options (if you haven't already):

Both to be found in: Processor type and features ->
- Symmetric multi-processing support
- SMT (Hyperthreading) scheduler support

Hope this helps.

Thanks for your attention
I have checked those parameters,they are set!But my issue is not solved.

Thanks for more help or guidance

Hi,

Other things I can come up with:

- Did you set the correct cpu (Processor family)
- Did you try setting mps tables (Enable MPS table)
- Did you change the Maximum number of CPU default (which is 8)

Maybe you can find a hint in the output of dmesg or /var/log/boot (or alike, if it exists).

And I do assume you rebooted after making the changes, recompiling and placing of the System.map and kernel image.

Hope this helps.

Thanks for your reply.
I answer your questions in order you asked:

- CPU is E5502 xeon - Dual Core.
- I did not find such setting on kernel. target kernel is 2.6.30.9 - Official kernel.
- This option is default.

I have tried but without any luck.

Thanks for any help or guidance

Hi,

I just downloaded 2.6.30.9 from kernel.org and checked for Enable MPS table: It is available under: Processor type and features -> Enable MPS table.

I do assume, looking at the CPU, that you have a X86_64 setup (BTW: the above setting is available with both x86 and x86_64).

You mention the cpu setting being: E5502 xeon - Dual Core. Do I assume correct that you choose Core 2/newer Xeon?
The E5502/Nehalem is not mentioned in the help part. Maybe you need to switch to Generic-x86-64

You haven't said if linux ran successfully before (with its default kernel). If that is the case, start that linux version and have a look at the output of /proc/cpuinfo to see if everything is ok, or if you still have missing cores.

You didn't say anything about checking the output of dmesg either. A lot of important info can be found there. The output of dmesg from your default linux (the one with the default kernel) can also be of great help, assuming that everything works ok.

Hope this helps.

Thanks a lot for your attention.
After enabling ACPI in kernel, All cpu's correctly are displayed.
Anyhow thanks again.