Re: Boot so slow it never completes, while Windows boots fine

["Alexander V. Makartsev" <avbetev@gmail.com>]

On 23.04.2020 19:57, Marcin Owsiany wrote:

TL;DR: My laptop starts ~20x slower than normal. Booting Debian hangs before the kernel starts. Windows 10 boots slow, but then works fine. Hardware problem?

More details:

I bought a Lenovo IdeaPad Flex 5 in April 2019. It came with Windows 10, I installed Debian buster on it (dual-boot with GRUB 2). Worked flawlessly (with secure boot!) for ~8 months.

In January 2020 after some reboot for the first time it started slow, and hung while booting Debian. Windows boots slow too, but once it's up it works just fine. BIOS SETUP UI is also very slow.

Since it might not be obvious what I mean, here is a recording, with detailed timeline in video description:

https://youtu.be/HCgO9UblqtI

After a few reboots it came back to normal. Then this effect came and went a few times, and now it's here for good. I cannot boot Debian at all. I tried leaving it booting overnight once and it didn't show any progress. Windows still works OK. Updating BIOS to the most recent version did not help.

I asked on the Polish Lenovo support forum, the response was that "this model does not support dual boot (sic!), they have had no similar reports in the past, and installing Linux on it might have caused the problem". I'm shocked.

Initially I thought this might have something to do with Windows updates, because on the first occasion it seems to have disappeared after Windows completed its scheduled update. But now I think it was just a red herring.

In my almost 30-year experience I have not encountered a problem which does not go away after a cold reboot, but does go away after Windows starts :-O

My only theories now are:

- a hardware problem (but why does it go away once Windows boots?)

- a botched CPU microcode update (but I suppose there are checksums which would prevent it from happening, so not likely).

Any thoughts?

Marcin

    I've watched your video and definitely I haven't seen anything like
    it before. I've seen slow BIOSes in the past, but not *that* slow.
    And it continues being slow even after it hits bootloader.
    I'd suspect either poorly tested Windows 10 update, which is known
    fact, Windows can update laptop BIOS without user's consent. Or some
    kind of malware/rootkit. These are rare, but still exist for BIOS
    and for UEFI. [1]
    It also could be a hardware problem where CPU\GPU runs on low
    frequency with failed attempts to rise it up. Or some device hogs
    some bus, generating interrupts in a loop, but never fails. The fact
    that after Windows starts it suddenly looks normal, could be because
    drivers take control over problematic device or Windows kernel
    applies some measures to circumvent known problem.
    
    In the first case BIOS should be reflashed with image made exactly
    for your laptop model, downloaded from official Lenovo website.
    Reset BIOS settings to defaults after reflash and set them up again.
    In the second case I'd check PSU and battery and removed it, if it
    is detachable. Check if cooling fan is working. Then gradually strip
    all devices, like M.2\NVMe\SATA drives, mini-PCIe WiFi adapter, DVD
    drive, keyboard, touchpad, any connected USB devices, etc. Connect
    external USB keyboard if needed. If you will be disconnecting laptop
    LCD screen, make sure to disconnect PSU and battery first, to avoid
    possible permanent damage to ICs on motherboard.
    This should be enough to tell if this is something user serviceable.
    If device stripping helps, then by adding devices back one by one
    you will find the culprit.
    
    I'd be interested to know exact laptop model\part number, for
    personal statistics and possible further research.
    
    
    [1]
    https://www.welivesecurity.com/wp-content/uploads/2018/09/ESET-LoJax.pdf
    
-- 
With kindest regards, Alexander.

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