Groups > linux.debian.user > #195755

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

From	David Wright <deblis@lionunicorn.co.uk>
Newsgroups	linux.debian.user
Subject	Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about CD-ROM
Date	2018-05-15 04:00 +0200
Message-ID	<vPxpT-6Y8-3@gated-at.bofh.it> (permalink)
References	(4 earlier) <vOmGd-3Bb-9@gated-at.bofh.it> <vP0WZ-4uO-1@gated-at.bofh.it> <vP2Fr-5zv-13@gated-at.bofh.it> <vP9dT-19U-1@gated-at.bofh.it> <vPtmi-4Gz-11@gated-at.bofh.it>
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On Mon 14 May 2018 at 23:29:43 (+0200), Pascal Hambourg wrote:
> Le 14/05/2018 à 02:02, David Wright a écrit :
> >On Sun 13 May 2018 at 19:08:48 (+0200), Pascal Hambourg wrote:
> >>
> >>Most of my early experience with UEFI boot comes from a rather old
> >>Intel motherboard. Beside crippled UEFI support (no UEFI boot from
> >>USB or SATA in AHCI mode), it had a couple of annoying requirements :
> >>- boot in legacy mode only if the MBR contains a partition entry
> >>with the boot flag set, regardless of whether the disk has a MSDOS
> >>or GPT partition table. This behaviour is beyond any common BIOS
> >>standard, but I have observed it on many other systems, mostly Dell
> >>and HP ;
> >
> >In the case of GPT, I assume the partition entry with the boot flag set
> >is the protective MBR.
> 
> Yes, as the protective GPT partition entry is the only non-empty entry.
> 
> >>- boot in EFI mode from GPT only if the protective partition entry
> >>in the MBR has the boot flag unset. I admit this requirement is part
> >>of the GPT specification, but really do not see the point in
> >>enforcing such a minor detail.
> >>
> >>Anyway, these two requirements put together make it impossible to
> >>boot in both legacy and EFI mode from the same GPT disk with this
> >>motherboard. However they allow to boot in both modes from the same
> >>MSDOS disk. But who still wants to use MSDOS format nowadays ?
> >
> >Is it impossible, then, to change the boot flag in a protective MBR?
> 
> Of cours not, but it is even less convenient than switching the boot
> mode in the firmware setup : boot the system, switch the boot flag,
> reboot the system...

Sorry, I thought impossible meant not possible. I agree that booting
up a system (that happens to be set to the wrong state) just to change
the boot flag and then reboot is a lot less convenient than the
process I use (which always lets you boot into the correct system
first time, and only requires action when you want to change over).

But the fact that you've experienced a crippled mobo does not IMHO
mean that some of the scenarios you could use on less crippled systems
shouldn't be discussed—nay, be treated as near impossible—in a web
page that's meant to be throwing light on the matter. As written, the
author just pours special magic sauce around, whatever that is.

Cheers,
David.

Thread

USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 18:20 +0200
  Re: USB Install Fails, Complains about CD-ROM Robert Menes <viewtiful.icchan@gmail.com> - 2018-05-11 18:40 +0200
    Re: USB Install Fails, Complains about CD-ROM Rick Thomas <rbthomas@pobox.com> - 2018-05-12 01:10 +0200
      Re: USB Install Fails, Complains about CD-ROM Kenneth Parker <sea7kenp@gmail.com> - 2018-05-12 03:40 +0200
      Re: USB Install Fails, Complains about CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-12 19:40 +0200
  Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-11 18:40 +0200
  Re: USB Install Fails, Complains about CD-ROM Curt <curty@free.fr> - 2018-05-11 19:10 +0200
    Re: USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 20:40 +0200
  Re: USB Install Fails, Complains about CD-ROM songbird <songbird@anthive.com> - 2018-05-11 19:50 +0200
    Re: USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 20:40 +0200
      Re: USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 21:30 +0200
      Re: USB Install Fails, Complains about CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-11 22:00 +0200
        Re: USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 22:20 +0200
          Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-11 22:40 +0200
            Re: USB Install Fails, Complains about CD-ROM Kent West <westk@acu.edu> - 2018-05-11 23:00 +0200
              Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-12 00:00 +0200
              Re: USB Install Fails, Complains about CD-ROM Brian <ad44@cityscape.co.uk> - 2018-05-12 12:30 +0200
            Re: USB Install Fails, Complains about CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-12 19:50 +0200
              Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-12 21:40 +0200
                Re: USB Install Fails, Complains about CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-13 10:20 +0200
                Re: Block sizes in ISOs. was: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-13 11:30 +0200
          UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-13 17:20 +0200
            Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-13 19:10 +0200
              Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-14 02:10 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-14 23:40 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-15 04:00 +0200
              Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM songbird <songbird@anthive.com> - 2018-05-14 12:40 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM Chris Ramsden <chris.ramsden@gmail.com> - 2018-05-14 14:40 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-14 16:00 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM Chris Ramsden <chris.ramsden@gmail.com> - 2018-05-14 17:00 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM songbird <songbird@anthive.com> - 2018-05-15 02:50 +0200
            Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about CD-ROM Stefan Monnier <monnier@iro.umontreal.ca> - 2018-05-14 15:20 +0200
              Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-14 16:40 +0200
                Re: UEFI/"BIOS" booting "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-14 18:00 +0200
                Re: UEFI/"BIOS" booting Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-14 23:50 +0200
                Re: UEFI/"BIOS" booting "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-15 09:00 +0200
                Re: UEFI/"BIOS" booting Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-16 00:20 +0200
                Re: UEFI/"BIOS" booting Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-16 23:50 +0200
                Re: UEFI/"BIOS" booting "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-17 13:00 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about CD-ROM Stefan Monnier <monnier@iro.umontreal.ca> - 2018-05-14 18:00 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-15 03:30 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-16 00:40 +0200
                Re: UEFI/"BIOS" booting, was Re: USB Install Fails, Complains about  CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-18 20:40 +0200
                Re: UEFI/"BIOS" booting Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-14 23:50 +0200
                Re: UEFI/"BIOS" booting David Wright <deblis@lionunicorn.co.uk> - 2018-05-15 03:40 +0200
                Re: UEFI/"BIOS" booting Pascal Hambourg <pascal@plouf.fr.eu.org> - 2018-05-16 00:40 +0200
                Re: UEFI/"BIOS" booting mess-mate <eric.m.c.declerck@gmail.com> - 2018-05-16 15:20 +0200
                Re: UEFI/"BIOS" booting David Wright <deblis@lionunicorn.co.uk> - 2018-05-18 20:50 +0200
  Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-13 04:20 +0200
    Re: USB Install Fails, Complains about CD-ROM Curt <curty@free.fr> - 2018-05-13 10:30 +0200
      Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-13 12:10 +0200
        Re: USB Install Fails, Complains about CD-ROM Curt <curty@free.fr> - 2018-05-13 14:10 +0200
          Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-13 14:50 +0200
        Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-13 19:00 +0200
          Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-13 20:20 +0200
            Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-14 00:40 +0200
              Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-14 13:30 +0200
                Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-14 16:50 +0200
                Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-14 18:20 +0200
                Re: USB Install Fails, Complains about CD-ROM David Wright <deblis@lionunicorn.co.uk> - 2018-05-14 20:10 +0200
                Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-14 22:10 +0200
                Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-14 23:00 +0200
                Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-15 01:20 +0200
                Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-15 09:10 +0200
                Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-17 23:40 +0200
                Re: USB Install Fails, Complains about CD-ROM "Thomas Schmitt" <scdbackup@gmx.net> - 2018-05-18 08:50 +0200
                Re: USB Install Fails, Complains about CD-ROM Mike Kupfer <mkupfer@alum.berkeley.edu> - 2018-05-15 01:10 +0200

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