A Blast From The Past

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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. Mark

8 thoughts on - A Blast From The Past

  • 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?

  • 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 repeated. 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. Mark
    —–Original Message—

  • You will either need an older computer or a different application. A
    company which only supports a .0 version of an OS usually means they aren’t really supporting their customers. They are expecting you to run an application on an OS without any security updates or improvements. There are 7 years of CVE’s in the kernel, libraries and other parts the customer has to live with if they want the application. Good luck.

  • This is absurd. The 7.0 kernel has so many vulnerabilities that are well known and well documented, they’re forcing you to run a kernel that can be trivially exploited. I would seriously push back with the manufacturer. Does it have a custom kernel module that it requires?
    Or did they only test it on RHEL or CentOS 7.0 and never updated their documentation?

    In the past, I’ve asked vendors that tried this kind of nonsense if they’re willing to indemnify their customers for any security issues that arise as a result of using their product. Feel free to list all the CVEs in the current CentOS 7 kernel. I see there are 1,125 CVEs mentioned in the kernel changelog. It won’t hold any legal water, most likely, but it might get someone to at least look closer at the issue.

  • But, if you only install the newer kernel, does your application work on it? If so, why not just run it that way?

    Apart from that, you could install a current distribution on the host and then let the application server run in a KVM instance. That way you can fine tune what kind of CPU/features are provided to the VM.

    Regards, Simon

  • Did you try to update your BIOS to the most recent version? Most BIOS updates add code to handle more recent CPUs.

  • Both Stephen and Jonathon have hit on this .. But you need to tell your vendor that a 7.0 kernel is vulnerable and that they need to support newer versions.

    There are so many security vulnerabilities in RHEL/CentOS from 7.0 to
    7.9 .. many of them remotely exploitable. And this is true for all packages, not just the kernel.

    If you have a RHEL/CentOS 7.0 machine running and touching the internet without security updates .. you probably no longer are running it. Certainly, not by yourself.