Date: Thu, 15 Jan 2009 11:35:21 -0800 From: Marcel Moolenaar <xcllnt@mac.com> To: Dimitry Andric <dimitry@andric.com> Cc: Randy Bush <randy@psg.com>, Luiz Otavio O Souza <lists.br@gmail.com>, George Neville-Neil <gnn@neville-neil.com>, Ben Kaduk <minimarmot@gmail.com>, current@freebsd.org Subject: Re: GEOM and moving to CURRENT from 7.1 Message-ID: <BC6ACB2A-CBC5-428B-8749-999B48B2D1C8@mac.com> In-Reply-To: <496F8D8A.1060508@andric.com> References: <FC3D3CF7-091B-4ECF-BE38-6C7751C20994@neville-neil.com> <alpine.BSF.2.00.0901112002080.3696@ibyngvyr.purzvxnyf.bet> <496D0364.2060505@psg.com> <47d0403c0901131335h46e7b151p3768de9a3e2c2027@mail.gmail.com> <EC370904A7B74B93887C79E120CA2835@adnote989> <085BEE07-BAE5-4A45-A14D-9587987FAA5C@mac.com> <496F44FA.1070004@andric.com> <48C1C477-B7BE-43B0-AC57-9DEB7BF9AA88@mac.com> <496F7347.4060007@andric.com> <A8E47805-888E-4282-8623-72A65B593D47@mac.com> <496F8D8A.1060508@andric.com>
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On Jan 15, 2009, at 11:24 AM, Dimitry Andric wrote: > On 2009-01-15 19:05, Marcel Moolenaar wrote: >>> Hmm, strangely enough I have multiple systems which really do use >>> ad0s1 >>> while installed DD using sysinstall, and have been using that >>> since years... >> This is a problem with sysinstall. It looks like DD is broken. >> MBR partitions are always created. > > Indeed, and the MBR itself is filled with /boot/boot1, plus a > partition > table. It is possible this was done to appease some PC BIOSes, > because > some of those refuse to boot, if there is no "valid" MBR with an > active > partition... You need a boot sector for the BIOS to jump into, but it doesn't have to be a MBR with slices. That's why a DD has something that looks an awful lot like a MBR in the first sector. It could very well be boot sector of an FAT* file system. > >> GEOM_PART correctly uses the >> BSD disklabel that's in the 2nd sector, but GEOM_MBR claims the >> MBR being unaware that the disk is DD. > > But how can this be, if I don't have GEOM_MBR in my kernel config? > (I'm > using GENERIC, in fact.) sys/i386/config DEFAULTS is included implicitly. It used to have GEOM_BSD and GEOM_MBR. >> libdisk is broken in that it should >> not create MBR slices for DD configurations to begin with... > > As stated above, this might be on purpose; enough braindead BIOSes out > there... :) Creating ambiguous, conflicting and/or overlapping partition information to work around broken BIOSes to support DD, is not a solution *if* it was on purpose. You want it to fail so that the user partitions the disk in the normal way. Put differently: if there are enough braindead BIOSes out there that won't support DD, then DD should be de-supported by FreeBSD. -- Marcel Moolenaar xcllnt@mac.com
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