Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

kso · 2024-08-28 15:12:49

Hi I am having trouble booting the archlinux installer on a p70 laptop with the Intel Xeon CPU E3-150SM v5 Skylake CPU with more than 3 cores.

I managed to install archlinux with multithreading disabled in the BIOS (so on 1 CPU) with UEFI boot on GPT file partition. However I want to preferably use all 8 cores.

Here is what I tried so far with BIOS boot (because UEFI boot just goes to a blank screen if I exceed 3 cores and BIOS boot produces some messages):

At the liveusb grub menu if I hit tab then add these kernel parameters:

loglevel=7 maxcpus=3 i915.preliminary_hw_support=1

then the boot works. If I set maxcpus > 3 it hangs at these last few lines below, so the max CPU cores I can use is 3.

rcu: Hierarchical SRCU implementation
rcu: oMax phase no-delay instances is 1000.
NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.
smp: Bringing up secondary CPUs ...
smpboot: x86: Booting SMP configuration:

If I wait for the liveusb to boot and provide a prompt with 3 cores enabled, then manually try to turn on an additional CPU core like this:

echo 1 > /sys/devices/system/cpu/cpu3/online

the console will hang also.

Does anyone have any suggestions on what I can try to enable all 8 cores to be turned on? Thanks very much in advance for the help.

gromit · 2024-08-29 17:33:02

Is this also the case with the linux-lts kernel?

seth · 2024-08-29 21:24:15

https://bbs.archlinux.org/viewtopic.php?id=289568
This used to be quite an issue half a year ago - though in retrospect also on suspiciously many raptor lakes…

Have you tried to bring cpu4 online and skip cpu3 (ie. is the issue w/ specifically core 3 or cores > 3)?

kso · 2024-08-30 13:47:11

Hi gromit, I enabled linux-lts with

pacman -S linux-lts

and regenerated the grub configuration with:

grub-install --target=x86_64-efi --bootloader-id=grub --efi-directory=/boot/efi

and then selected the LTS kernel during boot and it still hangs.

kso · 2024-08-30 13:49:44

Hi seth, I can no longer set maxcpus=3 to boot the liveusb in BIOS mode successfully anymore so I was not able to test. I can't remember the exact BIOS settings I used before in combination with the GRUB kernel parameters.

cryptearth · 2024-08-30 14:09:54

btw: the cpu is a E3-1505M v5 ... not S ... from Q3/2015 and gone EOL end of Q3/2022

@OP
have you tried older images like from around summer last year?
IIRC there're a couple threads about some change braking compatibility with older hardware which works fine when booted using older images

seth · 2024-08-30 14:15:48

@cryptearth, we've been there - this weird SMP breaks zstd decompression thing has affected CPUs of all generations and there's really nothing to change wrt "compatibility" because the "compatibility" is still SSE2 and I've tested actually this on a P4 Nehalem (which is about the oldest x86-64 CPU you can find) and it works fine. Slow and loud but fine.

Edit:
@kso

I can no longer set maxcpus=3 to boot the liveusb in BIOS mode successfully anymore so I was not able to test.

You mean the system doesn't boot even when limited to 3 CPUs?
What about one?
Can you boot anything, eg. https://grml.org ?

Last edited by seth (2024-08-30 14:17:42)

cryptearth · 2024-08-30 16:53:36

@seth
I just mentoined it because many others reported in thier threads that booting older images worked for them

kso · 2024-11-08 02:34:06

Hi all, sorry for the late reply.

@seth, I found out how to reset the BIOS configuration back to factory and now adding this to the kernel boot parameters will make the Arch Linux installer boot again:

loglevel=7 maxcpus=3 i915.preliminary_hw_support=1

This by default turns on CPUs 0 to 2. I'm then able to manually turn on CPUs 4 to 6 but after I try to turn on cpu 7, the Arch LInux installer hangs:

echo 1 > /sys/devices/system/cpu/cpu7/online

So here is what I found:

CPU 0 - works
CPU 1 - works
CPU 2 - works
CPU 3 - hangs installer
CPU 4 - works
CPU 5 - works
CPU 6 - works
CPU 7 - hangs installer

Trying 4 cores with these Kernel parameters also hangs the Arch Linux installer;

loglevel=7 maxcpus=4 i915.preliminary_hw_support=1

I'm happy with utilizing 6 out of 8 CPU cores for Arch Linux.

As for other distributions I confirmed that:

Grml boots perfectly utilising all 8 CPU cores without issues (which is incredible).
Debian installer boots perfectly utilising all 8 CPU cores without issues
CentOS 9 Stream boots perfectly utilising all 8 CPU cores without issues
Ubuntu installer hangs.

Perro Muerto · 2024-11-08 06:07:05

It sounds like you've done quite a bit of troubleshooting already. Since it's working with 3 cores but hanging with more, it could be a kernel or BIOS compatibility issue with that CPU.

seth · 2024-11-08 08:09:04

If you defer the activation of one of the "bogus" CPUs and keep "dmesg -W" running in one VT, does that get you any (error) messages when the CPU activates?
Can you boot w/ "mitigations=off noreplace-smp iommu=soft"?

You should probably also upload the grml output of

(uname -a; cat /proc/cmdline zcat /proc/config.gz) | curl -F 'file=@-' 0x0.st

Since the runtime activation causes it (immediately?), this does not just seem to be the decompression of the initramfs.

cryptearth · 2024-11-08 08:17:14

kso wrote:

CPU 0 - works
CPU 1 - works
CPU 2 - works
CPU 3 - hangs installer
CPU 4 - works
CPU 5 - works
CPU 6 - works
CPU 7 - hangs installer

would be interesting to know the physical-to-logical mapping here
if its 0+4, 1+5, 2+6, 3+7 could be a fault core
have you tried disable HT in bios and only use the 4 physical cores?

Arch Linux

#1 2024-08-28 15:12:49

Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#2 2024-08-29 17:33:02

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#3 2024-08-29 21:24:15

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#4 2024-08-30 13:47:11

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#5 2024-08-30 13:49:44

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#6 2024-08-30 14:09:54

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#7 2024-08-30 14:15:48

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#8 2024-08-30 16:53:36

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#9 2024-11-08 02:34:06

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#10 2024-11-08 06:07:05

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#11 2024-11-08 08:09:04

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

#12 2024-11-08 08:17:14

Re: Can't enable all 8 cores of Xeon CPU E3-150SM v5 Skylake CPU

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