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Date:      Mon, 17 Sep 2012 17:27:57 +0200 (CEST)
From:      Oliver Fromme <olli@lurza.secnetix.de>
To:        jhb@freebsd.org (John Baldwin)
Cc:        freebsd-hardware@freebsd.org
Subject:   Re: Booting from 3TB drive (UFS, BIOS)
Message-ID:  <201209171527.q8HFRw8q048154@lurza.secnetix.de>
In-Reply-To: <201209170850.09992.jhb@freebsd.org>

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John Baldwin wrote:
 > On Monday, September 17, 2012 8:41:09 am Oliver Fromme wrote:
 > > Problem is, the machine doesn't have an EFI BIOS and does
 > > *not* support GPT.  So it will use the compatibility MBR
 > > of the GPT, I assume.  And MBR isn't able to represent
 > > addresses beyond 2 TB, so the slice containing the boot
 > > partition will have to be within the first 2 TB of the
 > > drive, right?
 > 
 > No.
 > [...]
 > We support booting from GPT without EFI.  It will work fine.  The BIOS will 
 > see a PMBR that does indeed only cover 2TB, but that doesn't matter.  The 
 > whole point of the PMBR is to fool BIOSs.  :)  Tools that understand GPT (such 
 > as gpart) will see the GPT table and it's partitions.  FreeBSD's GPT bootstrap 
 > code (/boot/pmbr and /boot/gptboot) will see the GPT and use 64-bit LBAs for 
 > all I/O, so they can handle the partition being anywhere on the disk.

Ok, now I got it.
Thanks for bearing with me.  :)

Best regards
   Oliver


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Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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