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Re: UEFI question

From blind Pete <0123peter@gmail.com>
Newsgroups alt.os.linux
Subject Re: UEFI question
Date 2016-01-01 21:20 +1100
Organization A noiseless patient Spider
Message-ID <jf0ilc-fk8.ln1@psd.motzarella.org> (permalink)
References <n60hg5$h8a$1@dont-email.me> <n60j2j$2chn$1@saria.nerim.net> <n60khc$rip$1@dont-email.me>

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crankypuss wrote:

> Pascal Hambourg wrote:
> 
>> Hello,
>> 
>> crankypuss a écrit :
>>> from,
>>>    http://adam8157.info/blog/2015/04/hybrid-bootable-usb-stick-for-uefi-and-legacy-bios
>>> 
>>> "Legacy BIOS needs bootloaders to be installed into MBR
>> 
>> Yes.
>> 
>>> and the reserved space after it.
>> 
>> No. Anywhere else is fine too.
>> 
>>> UEFI only needs bootloaders in ESP(EFI System Partition).
>> 
>> Yes.
>> 
>>> There is no resource competition between legacy BIOS and UEFI
>>> requirements."
>> 
>> Yes, in theory. But practice may be different due to BIOS and UEFI
>> implementations.

Agreed, and you have to expect to trip over twice as many firmware 
bugs - that might interact in interesting ways.  

> Thanks Pascal.
> 
> I recognize that there are broken firmware implementations, that's how
> you learn which makers to avoid. <g>
> 
> From the theoretical correctness of those statements, I tend to conclude
> that a legacy BIOS system will remain unaffected by the presence/absence
> of an ESP, it's just some other partition not to be concerned with.
> However, the ESP only appears in GPT tables (doesnt' it?), so there's a
> question of whether (all non-broken) legacy BIOS systems will boot from
> a GPT-formatted device (and I've heard anecdotal comments that lead me
> to believe they will, but I haven't yet validated that myself).

Legacy BIOS firmware or UEFI firmware in legacy mode?  

It is possible to prepare a hybrid drive that looks like an MSDOS 
partitioned drive to a legacy BIOS, but is usable as a GPT drive.  
Such things are generally regarded as unreliable abominations.  

> It also leads me to conclude that (non-broken) UEFI firmware recognizes
> the ESP, but it's unclear whether it navigates the filesystem within the
> ESP or simply recognizes it by some set of flags and runs a first-stage
> loader from the recognized partition?

UEFI is required to recognize a fork of VFAT, but may recognize more.  

-- 
blind Pete
Sig goes here...  

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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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