bin/115406: [patch] gpt(8) GPT MBR hangs award BIOS on boot
Jeff Kletsky
jeff+freebsd at wagsky.com
Thu Jul 9 20:50:07 UTC 2009
The following reply was made to PR bin/115406; it has been noted by GNATS.
From: Jeff Kletsky <jeff+freebsd at wagsky.com>
To: bug-followup at FreeBSD.org, kent at khauser.net
Cc:
Subject: Re: bin/115406: [patch] gpt(8) GPT MBR hangs award BIOS on boot
Date: Thu, 09 Jul 2009 13:44:44 -0700
Based on the Intel Extensible Firmware Interface Specification, v 1.10,
the values present appear to be correct for current drives (anything
that exceeds the 500 MB CHS limit).
It would seem that the issue is compatibility of the BIOS with the Intel
spec (assuming that it is the definitive source), not the MBR
On all GUID Partition Table disks a Protective MBR (PMBR) in the first
LBA of the disk precedes
the GUID Partition Table Header to maintain compatibility with existing
tools that do not
understand GPT partition structures. The Protective MBR has the same
format as a legacy MBR,
contains one partition entry of OS type 0xEE and reserves the entire
space used on the disk by the
GPT partitions, including all headers. The Protective MBR that precedes
a GUID Partition Table
Header is shown in Table 11-7. If the GPT partition is larger than a
partition that can be
represented by a legacy MBR, values of all Fs must be used to signify
that all space that can be
possibly reserved by the MBR is being reserved.
Source:
http://www.intel.com/technology/efi/efiagree.htm
http://download.intel.com/technology/efi/docs/EFI_110.zip -- Page 11-14
(374/1084)
This notwithstanding, http://www.freebsd.org/cgi/query-pr.cgi?pr=133493
may still be part of the problem for the OP's systems.
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