From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: hpa@zytor.com Message-ID: <5292430D.6000709@zytor.com> Date: Sun, 24 Nov 2013 10:18:53 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 To: Karel Zak , Craig CC: util-linux@vger.kernel.org Subject: Re: ***Urgent***! Fdisk: GPT support utterly breaks hybrid MBR; *must* have disable option! :( References: <20131009141628.GB940@x2.net.home> <20131010111045.GA29199@x2.net.home> <20131011090442.GE14457@x2.net.home> In-Reply-To: <20131011090442.GE14457@x2.net.home> Content-Type: text/plain; charset=ISO-8859-1 List-ID: On 10/11/2013 02:04 AM, Karel Zak wrote: > > Yep. I don't want any "smart" solution there. All will be controlled > by users. > > (Well, in the default mode for non-expert users with standard PMBR we will > generate the MBR as expected by UEFI specification of course.) > There is one other useful mode for non-expert users, which is the one in which the current (hybrid) boot partition is manifest in the MBR (as well as as the GPT of course.) Changing the hybrid boot partition would change the MBR to match. From a UI perspective this could very easily be done by setting or removing a "hybrid" flag on a partition. One could potentially allow more than one hybrid partition, but when one then accounts for PMBR partitions, there is no guarantee that one can fit more than one unless the layout is suitable. In the worst case, one can always fit one: MBR: 1. Leading PMBR partition 2. Hybrid boot partition 3. Tailing PMBR partition In the best case, one can fit 3: MBR: 1. Hybrid partition 1 2. Hybrid partition 2 3. Hybrid partition 3 4. Tailing PMBR partition -hpa