Date: Mon, 08 Mar 2010 14:52:54 -0800 From: Marcel Moolenaar <xcllnt@mac.com> To: Andriy Gapon <avg@icyb.net.ua> Cc: Pete French <petefrench@ticketswitch.com>, freebsd-geom@freebsd.org Subject: Re: another gpt vs mbr (sanity) check Message-ID: <D90F9986-8BD1-46C8-995B-C79D9821B496@mac.com> In-Reply-To: <4B956533.2010900@icyb.net.ua> References: <E1Noh4B-000JjD-5u@dilbert.ticketswitch.com> <3158041B-8E00-4A87-8172-741C0AE57131@mac.com> <4B954367.3070804@icyb.net.ua> <FB4B329E-807F-4A47-A86B-AE3BC049A6DC@mac.com> <4B9544B3.80203@icyb.net.ua> <03BFAAEC-6C59-48EF-BED9-2E68ED03E2B6@mac.com> <4B956533.2010900@icyb.net.ua>
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On Mar 8, 2010, at 12:59 PM, Andriy Gapon wrote: > on 08/03/2010 22:23 Marcel Moolenaar said the following: >> On Mar 8, 2010, at 10:40 AM, Andriy Gapon wrote: >> >>> on 08/03/2010 20:36 Marcel Moolenaar said the following: >>>> On Mar 8, 2010, at 10:35 AM, Andriy Gapon wrote: >>>> >>>>> on 08/03/2010 19:55 Marcel Moolenaar said the following: >>>>>> On Mar 8, 2010, at 9:48 AM, Pete French wrote: >>>>>>> The queston is then, why isn't Windows treating it as GPT ? >>>>>> Ask Microsoft. So far I've only seen violations to the spec. At >>>>>> least Apple kept to the spirit of it... >>>>> According to my understanding it's the opposite as much as I hate saying this. >>>>> My understanding is that valid GPT scheme _must_ provide only a protective MBR, >>>>> i.e. MBR where there is only partition and it is of type 0xEE. >>>>> That is, any "hybrid MBR" is not a valid GPT scheme. >>>>> Google turns up a lot of stuff on this topic. >>>> Exactly. That is exactly the violation of the spec I was referring >>>> to. >>> I am not which part of what I said you meant by 'that'. >> >> All of it. > This hasn't added any clarity. > > So I'll just post one link about what position Apple had (note the past tense) > about protective MBR: > http://developer.apple.com/mac/library/technotes/tn2006/tn2166.html#SECPROTECTIVEMBR The document describes theory, but does not seem to describe reality: Revision 1.39: download - view: text, markup, annotated - select for diffs Mon Jun 26 00:32:54 2006 UTC (3 years, 8 months ago) by sobomax Branches: MAIN Diff to: previous 1.38: preferred, colored Changes since revision 1.38: +24 -5 lines Improve check for protective MBR. Instead of assiming that protective MBR should have only one entry of type 0xEE, consider protective MBR to be one, that has at least one entry of type 0xEE covering the whole unit. This makes GEOM_GPT compatible with disks partitioned by the Apple's BootCamp. Approved in principle by: marcel MFC After: 1 month In short, Apple bootcamp creates an invalid PMBR according to their own technote. FYI, -- Marcel Moolenaar xcllnt@mac.com
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