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Soon we will receive a 2-CPU mainboard with 2 Quad-Core Xeons on it. We have also a GNU system with Linux kernel (preconfigured). Currently, this Linux runs on a multi-core 1-CPU (Quad Core).

My question is if I will disable in BIOS one of the Xeons, will current Linux run on only one CPU? Will I need to change Linux configuration settings?

Here is important config settings:

CONFIG_NUMA=y
CONFIG_K8_NUMA=y
CONFIG_X86_64_ACPI_NUMA=y
CONFIG_NUMA_EMU=y
CONFIG_ACPI_NUMA=y
# CONFIG_X86_VSMP is not set
CONFIG_SMP=y
CONFIG_SUSPEND_SMP=y
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Yes it will work...but I have to ask the question...why would you do this?

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  • Thanks! This board is for server prototype. First we have to test our system on a new Xeon CPU, if it is enough CPU Performance then we will stay with cheaper 1-CPU(4Cores) on board solution for mass-production. If more performance will be required, then we will utilize 8 cores (2CPUx4Cores). – psihodelia Dec 11 '09 at 12:33
  • Can you also please specify why it will work? Maybe a link? – psihodelia Dec 11 '09 at 12:34
  • 2
    Why wouldn't it? As far as the OS is concerned, unless you are talking about a really large number of cores like 64 or more, 1-core or 8-core will work, with only the difference in performance. An SMP enabled Linux kernel will still work on 1-core, just without the multi-core magic. – sybreon Dec 11 '09 at 12:51
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A single CPU is just a special case of multiple CPUs, so the same code will work just fine.

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  • I'm not sure what you're saying here. Care to clarify? – MDMarra Dec 11 '09 at 12:38
  • Literally, the kernel boots up on the first CPU and enumerates other CPUs and boots them if it finds them installed and working. If there is only 1 cpu then it carries on just fine. – pjc50 Dec 11 '09 at 13:41

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