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Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about CD-ROM

Le 15/05/2018 à 03:23, David Wright a écrit :

In this particular instance (the Lenovo), its PDF says:
     The default boot mode for your computer is UEFI mode. If you need to
     install a legacy operating system, such as Windows (that is, any operating
     system before Windows 8)

This is so wrong. Windows has supported EFI since Vista.

AIUI what's unspecified is what you choose to put in the code section
of the MBR. In my case, and probably for most people here, it will be
Stage 1 of Grub.

Note : "stage 1" is a GRUB legacy thing. GRUB 2 calls it "boot image".

And if one has any sense, that will be pointing to a
BIOS boot partition, which is one of the first things I set up on a
GPT disk so that I can use it in my old BIOS machines. It makes things
far more bullet-proof if Grub knows there's a safe place to put its
later Stages. I suspect that systems without ones are likely to be the
ones causes much of the reported trouble.

Moreover, GRUB BIOS cannot be installed without embedding (in a BIOS boot partition or any other suitable location) when the /boot filesystem is anywhere else than a plain partition (LVM, RAID, crypto...) or a filesystem type which may move block around such as btrfs, defeating the hardcoded blocklists.