NetBSD Problem Report #52094

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Date: Sun, 19 Mar 2017 21:06:23 +0000 (UTC)
From: venture37@geeklan.co.uk
Reply-To: venture37@geeklan.co.uk
To: gnats-bugs@NetBSD.org
Subject: amd64 iso is only bootable in efi mode on legacy Mac
X-Send-Pr-Version: www-1.0

>Number:         52094
>Category:       install
>Synopsis:       amd64 iso is only bootable in efi mode on legacy Mac
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    install-manager
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 19 21:10:00 +0000 2017
>Closed-Date:    Thu Nov 05 13:23:10 +0000 2020
>Last-Modified:  Thu Nov 05 13:23:10 +0000 2020
>Originator:     Sevan Janiyan
>Release:        7.99.66
>Organization:
>Environment:
>Description:
The amd64 is bootable in EFI mode or by conventional means (is El Torito the correct term?).
On a legacy mac, the EFI boot manager built into the system firmware (accessed by holding option) will only present the EFI boot mode.

On a more recent mac, you'er present with two boot options for a medium.
>How-To-Repeat:
Boot the amd64 iso on a intel Mac, in this case, a 2007 17" MacBook Pro.
>Fix:

>Release-Note:

>Audit-Trail:

State-Changed-From-To: open->feedback
State-Changed-By: maya@NetBSD.org
State-Changed-When: Sun, 03 Jun 2018 07:00:14 +0000
State-Changed-Why:
I'm confused, what is the bug? we now support EFI (could be better), so this shouldn't be a problem, but if it is - it's a firmware one, a choice not to support legacy boot. We'll probably have more machines like this in the future.


From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 09:43:47 +0100

 On 03/06/2018 08:00, maya@NetBSD.org wrote:
 > I'm confused, what is the bug? 

 You are meant to have 2 options from the medium.

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 10:09:49 +0100

 On 03/06/2018 09:45, Sevan Janiyan wrote:
 >  On 03/06/2018 08:00, maya@NetBSD.org wrote:
 >  > I'm confused, what is the bug? 
 >  
 >  You are meant to have 2 options from the medium.

 Specifically, the ability to boot in legacy (BIOS emulation) mode is
 missing, you can only boot in the modern EFI mode.

From: maya@netbsd.org
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 10:40:15 +0000

 Legacy boot is optional, firmware is allowed to be EFI-only.
 It's not unexpected for a machine designed to run mostly one OS to skip
 the backwards compatibility part, and EFI-only will get more common as
 time goes on.

From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 12:40:47 +0200

 On Sun, Jun 03, 2018 at 09:10:00AM +0000, Sevan Janiyan wrote:
 >  Specifically, the ability to boot in legacy (BIOS emulation) mode is
 >  missing, you can only boot in the modern EFI mode.

 Sorry, but I don't get what you mean either.
 Firmware decides whether you boot in lgeacy (BIOS) or UEFI mode.

 How is the amd64 install or iso image involved in this at all?

 Martin

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 11:58:27 +0100

 On 03/06/2018 11:45, maya@netbsd.org wrote:
 >  Legacy boot is optional, firmware is allowed to be EFI-only.
 >  It's not unexpected for a machine designed to run mostly one OS to skip
 >  the backwards compatibility part, and EFI-only will get more common as
 >  time goes on.

 System in question is from 2007, on a more recent system (say 2012), you
 are given the option to do both which contradicts that theory and while
 x86 Apple systems initially shipped without any legacy support, this was
 added back in later down the line.


 Sevan

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 12:00:41 +0100

 On 03/06/2018 11:45, Martin Husemann wrote:
 >  Firmware decides whether you boot in lgeacy (BIOS) or UEFI mode.
 >  
 >  How is the amd64 install or iso image involved in this at all?

 The EFI (not UEFI) boot manager on Apple hardware present 2 boot options
 from a single boot medium. One which utilises the EFI boot loader if
 present and the conventional (legacy BIOS) boot loader and you can
 select which to use.


 Sevan

From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 13:09:09 +0200

 On Sun, Jun 03, 2018 at 11:05:01AM +0000, Sevan Janiyan wrote:
 >  The EFI (not UEFI) boot manager on Apple hardware present 2 boot options
 >  from a single boot medium. One which utilises the EFI boot loader if
 >  present and the conventional (legacy BIOS) boot loader and you can
 >  select which to use.

 So how does it decide whether to offer the legacy one? Testing for the
 EFI boot partition is easy, but I am not sure how it can tell a working
 MBR from a dummy.

 Martin

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 12:09:30 +0100

 On 03/06/2018 12:00, Sevan Janiyan wrote:
 >>  How is the amd64 install or iso image involved in this at all?

 I mean that though our boot uefi media contains loaders for modern &
 legacy modes, you are not present with the option to utilise the legacy
 mode, despite it being there and available.
 On more modern systems, it's possible to attempt to boot in either mode.
 I'm pointing at our install media because it's possible to boot other
 operating systems which lack EFI/UEFI support using legacy mode on such
 a system.

 Seva

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 12:15:35 +0100

 On 03/06/2018 12:10, Martin Husemann wrote:
 > So how does it decide whether to offer the legacy one? Testing for the
 >  EFI boot partition is easy, but I am not sure how it can tell a working
 >  MBR from a dummy.

 I'm not sure how it decides because it's all automagic and while you can
 add a third party console (rEFIt / rEFInd), you essentially end up
 chain-loading for one and our media works with such tools usually which
 doesn't help shed any light.

 Sevan

From: Martin Husemann <martin@duskware.de>
To: gnats-bugs@NetBSD.org
Cc: install-manager@netbsd.org, gnats-admin@netbsd.org,
	netbsd-bugs@netbsd.org, venture37@geeklan.co.uk
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 13:23:06 +0200

 On Sun, Jun 03, 2018 at 11:20:01AM +0000, Sevan Janiyan wrote:
 >  On 03/06/2018 12:10, Martin Husemann wrote:
 >  > So how does it decide whether to offer the legacy one? Testing for the
 >  >  EFI boot partition is easy, but I am not sure how it can tell a working
 >  >  MBR from a dummy.
 >  
 >  I'm not sure how it decides because it's all automagic[..]

 Yes, I understand, but if it is not documented, it is impossible
 to fix for anyone that does not have one of the affected Macs (and
 even with having the machine it sounds like pure trial and error).

 Martin

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094 (amd64 iso is only bootable in efi mode on legacy
 Mac)
Date: Sun, 3 Jun 2018 12:29:55 +0100

 On 03/06/2018 12:25, Martin Husemann wrote:
 > Yes, I understand, but if it is not documented, it is impossible
 >  to fix for anyone that does not have one of the affected Macs (and
 >  even with having the machine it sounds like pure trial and error).

 I agree. Let me see what I can find out, might be a slight delay in
 responding pre-BSDCan.


 Sevan

From: Sevan Janiyan <venture37@geeklan.co.uk>
To: gnats-bugs@NetBSD.org
Cc: 
Subject: Re: install/52094: amd64 iso is only bootable in efi mode on legacy
 Mac
Date: Thu, 5 Nov 2020 13:13:22 +0000

 Please close this PR.


 Sevan

State-Changed-From-To: feedback->closed
State-Changed-By: martin@NetBSD.org
State-Changed-When: Thu, 05 Nov 2020 13:23:10 +0000
State-Changed-Why:
Closing on submitters request


>Unformatted:

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