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I have installed Debian Stretch (9.6) on UEFI-based platform
Everything went fine, but I cannot... boot to the system.
After the GRUB2 starts the image all I get is:

Loading Linux 4.9.0-8-amd64
Loading initial ramdisk ...

and it freezes...

Once I go to UEFI and enable CSM (The Compatibility Support Module) it is possible to boot to the Debian.

However I don't want this CSM enabled (it adds startup overhead).
What is the actual cause of system not booting without CSM? I'm guessing it is the distro and the only thing is to try testing / sid ?
Do I have some other options to boot Debian 9.6 without CSM (legacy)?

  • 2
    The CSM fundamentally changes how the firmware presents itself to the operating system, effectively emulating an old BIOS. The UEFI requires a different bootloader, and also a special EFI System Partition (ESP). For what you will need to do, see blog.getreu.net/projects/legacy-to-uefi-boot – Johan Myréen Jan 6 at 23:13
  • I'm aware of that, I do have ESP partition with debian loader. Moreover d-i installer is aware of UEFI/BIOS and prepares proper loader. I've installed in pure UEFI mode. Yet still only in CSM mode I can load the Debian... – lakier Jan 7 at 9:01
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I think it is worth posting a solution.

Of course EFI system partition is required, but debian installer already prepares that automatically...

What actually is not that obvious and caused 'black screen' on the boot was BIOS setting: "Above 4G decoding" enabled.
Turning it off causes the system to boot properly
Yet, I still don't know how important that setting is and what are the drawbacks of switching it off (I found this solution here)

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