Re: UEFI grub install fails

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Steve McIntyre <steve@einval.com> wrote:
> the UEFI spec also
> requires that implementations support MBR-partitioned disks for the
> ESP. [...]
> While UEFI implementations can be buggy, I don't think I've seen one
> yet that doesn't cope with this section.

Isn't such a bug in some old EFI the reason why the Debian amd64 ISOs
have the mockup of a GPT although mainly luring by a MBR partition
of type 0xEF ?

As eye-witness and accessory i know that this partition table jackalope
stems from
  https://mjg59.dreamwidth.org/11285.html
by Matthew Garrett, where one can read:

  "[...] it turns out that there are some systems that refuse to
   BIOS-boot off GPT media. So we need an MBR partition map."

and also:

  "Why have a GPT at all? The EFI spec says that machines should boot
   fine from an MBR partition. Sadly, not all seem to."


Actually, after 13 years of pondering, i believe the first problem was
with the legacy BIOSes which don't boot without seeing an MBR partition
with Boot flag set. UEFI GPT specs on the other hand forbid that flag
withinthe Protective MBR which announces GPT.
But obviously some half-brained EFI implementation was satisfied with
seeing a GPT header block without prior Protective MBR and possibly
booted from the GPT partition. (Maybe it was absurd enough to
eventually boot from the MBR partition.)


Have a nice day :)

Thomas