Re: UEFI question

From	crankypuss <invalid@invalid.invalid>
Newsgroups	alt.os.linux
Subject	Re: UEFI question
Date	2016-01-01 15:17 -0700
Organization	A noiseless patient Spider
Message-ID	<n66tp4$6q5$1@dont-email.me> (permalink)
References	(1 earlier) <n60j2j$2chn$1@saria.nerim.net> <n60khc$rip$1@dont-email.me> <jf0ilc-fk8.ln1@psd.motzarella.org> <n65q35$51q$1@dont-email.me> <n66osl$16ho$1@saria.nerim.net>

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Pascal Hambourg wrote:

> crankypuss a écrit :
>> 
>> I have multiple linux root partitions on a single USB stick.  Some of
>> these partitions contain only one kernel, others contain several, but
>> they are all bootable linux installs, and they are all 32-bit builds.
>> 
>> Each such USB stick is used for backup/rescue/recovery.  I need to
>> boot any of these on 3 different machines which have different
>> firmware:
>> 
>> Acer AOA150: 32-bit processor, legacy BIOS.
>> 
>> Dell XPS13: 64-bit processor, UEFI Firmware, but will boot in legacy
>> mode if the boot partition is physical (not logical) and its boot
>> flag is set.
> 
> "Physical" ? Do you mean "primary" ?

Yes, sorry, my terminology is not always quite perfect, I still 
occasionally call a symlink a "synonym", and so forth; old terms die 
hard, my bad.

>> ASUS T150: 64-bit processor with 32-bit UEFI Firmware, will not even
>> consider booting a non-UEFI device.
>> 
>> I've been successfully handling the Acer/Dell cases with MSDOS
>> partition table having one physical partition (boot flag set, grub2
>> installed) followed by an extended partition containing the other
>> distros, one per partition.
>> 
>> I'm trying to understand how to add the ASUS case to the mix.  As far
>> as I can tell the ASUS pushes me to using a GPT partition table, but
>> beyond that the details get a little fuzzy.
> 
> If the UEFI firmware complies to the UEFI specification, it should
> accept to boot from an MSDOS partition table. The drive must contain a
> small EFI system partition of type 0xEF formated as FAT (I don't know
> if it must be primary or can be logical)

It also needs a couple flags set, and I don't know about the 
primary/logical requirement either.  I've been busy enough with other 
things and researching stuff I don't understand that I just got back to 
writing a little code for a change this morning.

I could just try a bunch of stuff, but testing it for bootability on 3 
different systems makes pure trial-and-error a bit too time-consuming.

> where you can install GRUB
> EFI or another EFI compatible boot loader as the default loader
> EFI/boot/bootx64.efi for a 64-bit firmware or EFI/boot/bootia32.efi
> for a 32-bit firmware. Beware, there are 64-bit machines with 32-bit
> UEFI firmware.

Yes, my ASUS T100 is a 64-bit machine with 32-bit UEFI firmware.  Since 
I'm maintaining binary compatability on 3 differing systems, and one of 
them is 32-bit only, all my installs are 32-bit.

> If the firmware cannot boot from an MSDOS partition table, you'll have
> to convert the table to GPT with tools such as gdisk, and reinstall
> the legacy and EFI bootloaders. GRUB PC (BIOS) likes to have a small
> "BIOS boot" partition on a GPT disk, but it is not mandatory.

The test stick I'm working with has been converted by gdisk (as I 
recall) but mostly I'm working on the code to collect information about 
the various partitions available on various block devices.

Thanks P.

-- 
http://totally-portable-software.blogspot.com
  [Sun Nov 22: "Total Portability is not binary"]

Thread

UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-30 05:11 -0700
  Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-12-30 13:35 +0100
    Re: UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-30 06:03 -0700
      Re: UEFI question Bit Twister <BitTwister@mouse-potato.com> - 2015-12-30 13:48 +0000
        Re: UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-30 14:10 -0700
          Re: UEFI question "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2015-12-30 16:26 -0500
            Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-12-31 10:21 +0100
              Re: UEFI question "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2015-12-31 08:50 -0500
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-12-31 16:19 +0100
                Re: UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-31 11:51 -0700
                Re: UEFI question Bit Twister <BitTwister@mouse-potato.com> - 2015-12-31 19:34 +0000
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-12-31 21:52 +0100
                Re: UEFI question "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2016-01-01 18:58 -0500
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-02 02:19 +0100
                Re: UEFI question blind Pete <0123peter@gmail.com> - 2016-01-03 16:30 +1100
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-03 11:12 +0100
                Re: UEFI question Eef Hartman <E.J.M.Hartman@gmail.com> - 2016-01-03 12:44 +0000
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-03 15:16 +0100
                Re: UEFI question blind Pete <0123peter@gmail.com> - 2016-01-03 23:12 +1100
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-03 15:22 +0100
                Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-02 01:53 -0700
                Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-02 12:08 +0100
                Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-02 10:47 -0700
            Re: UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-31 02:37 -0700
          Re: UEFI question Bit Twister <BitTwister@mouse-potato.com> - 2015-12-30 22:18 +0000
      Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2015-12-31 10:16 +0100
        Re: UEFI question crankypuss <invalid@invalid.invalid> - 2015-12-31 02:46 -0700
      Re: UEFI question blind Pete <0123peter@gmail.com> - 2016-01-01 21:20 +1100
        Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-01 05:08 -0700
          Re: UEFI question Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2016-01-01 21:51 +0100
            Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-01 15:17 -0700
              Re: UEFI question Bit Twister <BitTwister@mouse-potato.com> - 2016-01-01 23:06 +0000
                Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-02 02:16 -0700
                Re: UEFI question Bit Twister <BitTwister@mouse-potato.com> - 2016-01-02 10:04 +0000
                Re: UEFI question crankypuss <invalid@invalid.invalid> - 2016-01-02 03:39 -0700
                Re: UEFI question blind Pete <0123peter@gmail.com> - 2016-01-03 15:20 +1100
          Re: UEFI question blind Pete <0123peter@gmail.com> - 2016-01-03 15:14 +1100

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