[CentOS] A Blast from the past

Tue Aug 17 16:02:02 UTC 2021
Mark Woolfson <mrw at mwcltd.co.uk>

Thank you for your feedback.

Unfortunately the manufacturer of our application software will only support
it on RHEL/CentOS 7.0. I have asked and that is all they say.
When the CentOS 7.0 boots it does not recognise the CPU ID, flags it as a
soft error then continues.
The Haswell and the Ice Lake both have 28 cores but different frequencies.
A couple of clues. At the boot prompt the server cooling fans are running
slowly. When it hangs, after a short delay, the fans run faster and this is
Also, when it hangs the keyboard is unresponsive and the server status LED's
state that all is okay.
If Intel adhere to the x86_64 standard for their processors then surely the
only difference would be the addition functionality.
I am trying to find a resolution as this particular application is perfect
for our requirements.
-----Original Message-----
From: CentOS <centos-bounces at centos.org> On Behalf Of Phil Perry
Sent: 17 August 2021 16:43
To: centos at centos.org
Subject: Re: [CentOS] A Blast from the past

On 17/08/2021 16:34, Simon Matter wrote:
>> Hello,
>> Can you please help with an interesting problem.
>> I have an Intel Haswell based processor with CentOS 7.0 with an early 
>> kernel booting and running perfectly.
>> I changed the processor to an Ice Lake and I get the problem below 
>> when I boot the working Haswell disk.
>> The boot process hangs almost immediately and when I remove the 'quiet'
>> boot
>> parameter I see that it hangs randomly, usually with a high CPU 
>> number, when SMPBOOT is starting up the cores.
>> The only solution I have found is to boot with the 'nr_cpus=8 (could 
>> be any low number), update to the latest kernel then reboot with the 
>> 'nr_cpus=8'
>> parameter removed.
>> On examination there are no problems with CentOS 7.4 and above but 
>> there are with CentOS 7.3 and below.
> I think the issue is quite clear here: the newer CPU is not handled 
> correctly by the old kernel - maybe it even doesn't know this CPU type 
> and doesn't know how to detect the number of cores it has.
> I don't think there is a better solution than what you already did.
> Regards,
> Simon

Exactly what I was thinking. CentOS 7.0 released in 2014, Intel Ice Lake
released at least 5 years later so there will be no support for Ice Lake in
the CentOS 7.0 kernel. I'm surprised there is any support in 7.4. Why are
you not using the latest release?

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