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    SubjectRe: Early kernel panic in dmi_decode when running 32-bit kernel on Hyper-V on Windows 11
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    Hello,


    Am 16.04.2024 um 01:31 schrieb Michael Kelley:

    > Can you give me details of the Hyper-V VM configuration? Maybe
    > a screenshot of the Hyper-V Manager "Settings" for the VM would
    > be a good starting point, though some of the details are on
    > sub-panels in the UI.

    It used to be possible to export Hyper-V VM settings as XML, but
    apparently that option has been removed in Win2016/Win10, in favor of
    their own proprietary binary .vmcx format...

    Also, maybe it matters what else Hyper-V is doing. I've installed both
    WSL and WSA, and Windows Defender is using Core Isolation Memory
    Integrity. I have also enabled support for nested virtualisation in the
    Host/Network Switch, but not in that VM.

    Anyway, I just created two new VMs (one of each generation) with no hard
    disk and everything else default, added a DVD drive to the SCSI
    controller of Gen2 (which Gen1 already had on its IDE controller),
    disabled Secure Boot on Gen2 and added a second vCPU to Gen1 (which Gen2
    already had).

    Afterwards, Gen2's dmidecode looks like the summary you posted, and Gen1
    reproduces the issue.

    > I'm guessing your 32-bit Linux VM is
    > a Generation 1 VM. FWIW, my example was a Generation 2 VM.

    Very interesting that Gen2 boots 32-bit Linux better than Gen1 (there is
    a delay during hardware autoconfigruation (systemd-udevd) for about 30
    seconds when booting Gen2 which I did not investigate yet), despite the
    documentation claiming not to use Gen2 for any 32-bit Host OSes.

    So I assume this only applies to crappy OSes that directly couple their
    bitness to the bitness of the UEFI firmware.

    To be fair, the live media I'm using uses Grub's "non-compliant" Linux
    loader that bypasses the kernel's EFI stub. When trying with Grub's
    "linuxefi" loader, Linux does not boot either, as expected. (On the Gen1
    VM, the panic happens regardless whether I use grub's linux16 or linux
    loader, and also with SYSLINUX/ISOLINUX loader).

    > When you ran a 64-bit Linux and did not have the problem, was
    > that with exactly the same Hyper-V VM configuration, or a different
    > config?

    All my tests were performed with a single (Gen1) VM, and the only
    setting I changed was the number of vCPUs.


    Regards,


    Michael


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