[Solved] Guest has only 1 CPU but configured for 2

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Stache
Posts: 2
Joined: 8. Jan 2022, 19:17

[Solved] Guest has only 1 CPU but configured for 2

Post by Stache »

My host is running VirtualBox 5.2.42_Ubuntur137960 on Ubuntu server 18.04.6 64bit with 31G RAM and no GUI (I run everything headless).

One of my guests, running Ubuntu 20.04.3 64bit, 8G RAM and Guest Additions 5.2.42 is configured to use 2 CPUs but only sees 1. It was originally configured for 1 CPU but I modified the config to 2 later on.

Why can't my guest see the 2nd CPU?

I'm a long time VirtualBox user but first time poster.
THANK you in advance.
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fth0
Volunteer
Posts: 5668
Joined: 14. Feb 2019, 03:06
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Linux, Windows 10, ...
Location: Germany

Re: Guest has only 1 CPU but configured for 2

Post by fth0 »

Stache wrote:Why can't my guest see the 2nd CPU?
Because the I/O APIC is disabled in the VM configuration. The VirtualBox Manager would have forced you to enable it. ;)
Stache
Posts: 2
Joined: 8. Jan 2022, 19:17

Re: Guest has only 1 CPU but configured for 2

Post by Stache »

This fixed it:

Code: Select all

vboxmanage modifyvm <VM Name> --ioapic on
Thanks fth0!! :D
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