Arch Linux

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Only one of my 4 cpu cores is detected.

Running lscpu gives me this:

Architecture:            x86_64
CPU op-mode(s):        32-bit, 64-bit
Address sizes:         39 bits physical, 48 bits virtual
Byte Order:            Little Endian
CPU(s):                  1
On-line CPU(s) list:   0
Vendor ID:               GenuineIntel
Model name:            Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
CPU family:          6
Model:               142
Thread(s) per core:  1
Core(s) per socket:  1
Socket(s):           1

The i5-8250U is a quad-core cpu, but only one core is being detected. What can I do to enable the rest of the cores?

My installation will not boot with acpi enabled (there is a black screen and it shuts off).

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,732

Website

Re: Only one of my 4 cpu cores is detected.

What does running nproc say?  Do you have anything disabled in the BIOS?

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

nproc just says 1. I have SGX disabled in the bios.

graysky

Wiki Maintainer

From: :wq

Registered: 2008-12-01

Posts: 10,732

Website

Re: Only one of my 4 cpu cores is detected.

Some BIOS allow you to enable/disable CPU options.  I don't recall seeing one that allows disabling physical cores though.  Not sure what to tell you.

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

Yeah I only posted this because I couldn't find any information anywhere on how to fix this.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,491

Re: Only one of my 4 cpu cores is detected.

My installation will not boot with acpi enabled

Notebook? What exact model?

Did you try any other of the ACPI options?
https://raw.githubusercontent.com/torva … meters.txt

How many parallel MS Windows installations are on that system?

Last edited by seth (2021-12-30 16:29:59)

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I believe my notebook is a "MEDION AKOYA P6685-i5-256F8 Notebook 39.6 cm (15.6") Full HD 8th gen Intel® Core™ i5 8 GB DDR4-SDRAM 256 GB SSD NVIDIA® GeForce® MX150 Wi-Fi 5 (802.11ac)". I have one windows installation, but it is on another drive. I have tried acpi= on, off, force, noirq, strict, rsdt and copy_dsdt, but only off boots. Should I try the other options in the document?

Last edited by GreenIcedTea (2021-12-30 23:46:00)

2ManyDogs

Forum Fellow

Registered: 2012-01-15

Posts: 4,648

Re: Only one of my 4 cpu cores is detected.

What kernel are you using (what does 'uname -r' report)? If you are using the mainline kernel, have you tried the LTS kernel? If you boot the install image does nproc still see only one core? Have you tried a live iso from a different linux distro?

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

uname -r

 5.15.11-arch2-1 

I think I am using the mainline kernel. I have not tried the LTS kernel. I will try booting into the live version of pop!os and see if I have the same problem.

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I booted into the live version of pop!os (I had to disable acpi for this), and running lscpu and nproc --all give the same output. I believe I no longer have the original installation medium.

Last edited by GreenIcedTea (2021-12-31 01:28:59)

loqs

Member

Registered: 2014-03-06

Posts: 18,964

Re: Only one of my 4 cpu cores is detected.

Try iommu=soft pci=noacpi
Edit:
If that does not work try the strings from DSDT

Last edited by loqs (2021-12-31 01:40:30)

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I tried iommu=soft pci=noacpi which booted when acpi=off was included. Running lscpu and nproc --all still gives the same output. I will try DSDT next.

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I tried changing the acpi_os_name and acpi_osi parameters, but still no changes.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,491

Re: Only one of my 4 cpu cores is detected.

I have one windows installation

3rd link below. Mandatory. Likely the cause of the acpi issues, possibly of your lost cores.

Fyi:

but it is on another drive.

Completely irrelevant. The  problem is w/ your BIOS/ACPI, not your hard drive.

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

After disabling fastboot on windows, my cores are still not detected and I still need acpi=off. Should I reinstall arch now that fastboot is disabled?

Last edited by GreenIcedTea (2021-12-31 16:19:23)

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,491

Re: Only one of my 4 cpu cores is detected.

You should reboot windows and linux a couple of times (semi-vodoo) to make sure the ACPI is "unconfused" about the state.
But re-installation won't do anything.

Could you boot the installation iso w/o acpi=off?

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I couldn't boot the installation iso without acpi=off. I'm in the process of rebooting Windows and arch right now (still with acpi=off).

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I have restarted both windows and Linux (with acpi=off) about 4 times now and the problem still persists.

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 76,491

Re: Only one of my 4 cpu cores is detected.

Are there any BIOS updates available?
(You could try a bunch of live distros to see whether *any* works, but this is probably some off-spec acpi implementation…)

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GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

I looked on the manufacturer's website, and they don't allow you to download firmware updates because they say it is included in windows updates. I will try seeing if there is a windows update that has an updated firmware.

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

There was no updated firmware that I could find.

GreenIcedTea

Member

Registered: 2021-12-30

Posts: 20

Re: Only one of my 4 cpu cores is detected.

Does it matter that I am running the arch installation off an external hard drive?

arch_kk_linux

Member

Registered: 2017-02-17

Posts: 54

Re: Only one of my 4 cpu cores is detected.

I couldn't boot the installation iso without acpi=off. I'm in the process of rebooting Windows and arch right now (still with acpi=off).

luckily for me having removed acpi=off from by commandline arguments worked like a charm. now all cores are visible. the culprit is adding acpi = off. seems u have to some how boot with out adding acpi=off. (Ps: I dont have dual boot. I'm just running arch)

2ManyDogs

Forum Fellow

Registered: 2012-01-15

Posts: 4,648

Re: Only one of my 4 cpu cores is detected.

Closing this old thread.