Date: Fri, 27 Dec 2013 11:24:44 -0500 From: Thomas Hoffmann <trh411@gmail.com> To: Warren Block <wblock@wonkity.com> Cc: Mathieu Arnold <mat@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, freebsd-stable@freebsd.org Subject: Re: FreeBSD 10.0-RC3 Now Available Message-ID: <CAB7-od=i7xitXJU=-M%2BKLkH4iNw-mYbvZsMNjzitocfLB2ErLA@mail.gmail.com> In-Reply-To: <alpine.BSF.2.00.1312270859430.32365@wonkity.com> References: <20131226162521.GK2009@glenbarber.us> <CA%2BWntOt26JXT3Bh8ccSM-fQ726c2Hy3F06n2iDbu3pLBXjn-AA@mail.gmail.com> <20131226212158.GD13109@glenbarber.us> <CACuV5sCjjsjFK9AjJ7saRPpDktwxf1rd6a-M2FKXXYf-EaBy2w@mail.gmail.com> <BCB09816844D0B52B1EFE964@atuin.in.mat.cc> <CACuV5sD2Cw=iZ=uE8BjcV6j8-Bc8ppChQ=ZPKZ7uFTXQLmhCxQ@mail.gmail.com> <2F6DABD655B7C3230EC0F15D@ogg.in.absolight.net> <CAB7-odmH-b=%2B_-BwF1jt7EMdTxpK-P%2Bw%2Bp6Ce9-k7mRvXpLzog@mail.gmail.com> <38B0C411B75D7482B92033D2@ogg.in.absolight.net> <alpine.BSF.2.00.1312270859430.32365@wonkity.com>
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After I posted, it occurred to me to check out the ../bsdinstall/scripts/zfsboot script to see how the boot code was laid down when the MBR was created. It shows only: dd if=3D/boot/zfsboot of=3D/dev/ada0s1 count =3D1 But, adding to my confusion, the FreeBSD wiki for ZFS on root (MBR-style) shows something very close to what Mathieu suggested. Unfortunately, I'm using an iMac with FreeBSD as the only OS. MBR is the only way I can get it to boot after an install. Looks like I've got some testing (and possible system restores) ahead of me= . Thanks. On Fri, Dec 27, 2013 at 11:08 AM, Warren Block <wblock@wonkity.com> wrote: > On Fri, 27 Dec 2013, Mathieu Arnold wrote: > > +--On 27 d=E9cembre 2013 10:28:07 -0500 Thomas Hoffmann <trh411@gmail.co= m> >> wrote: >> | All the examples I've seen for updating bootcode assume GPT. If one ha= s >> | MBR (as I do) and assuming the following basic scheme: >> | >> | gpart show ada0 >> | =3D> 63 976773105 ada0 MBR (466G) >> | 63 976773105 1 freebsd [active] (466G) >> | >> | gpart show ada0s1 >> | =3D> 0 976773105 ada0s1 BSD (466G) >> | 0 943218736 1 freebsd-zfs (450G) >> | 943218736 33554369 2 freebsd-swap (16G) >> | >> | would the equivalent bootcode statement be: >> | >> | gpart bootcode -b /boot/pmbr -p /boot/zfsboot ada0s1 >> > > No, the PMBR is for GPT partitioning only. > > > | where the boot code is /boot/zfsboot (rather than /boot/gptzfsboot) an= d >> | ada0s1 is the slice on which FreeBSD is installed? >> >> Hum, no, if you're using MBR and not GPT, you can't use gpart, >> > > Why not? gpart is not GPT-specific. It handles MBR and BSDlabel bootcod= e > correctly. > > > you have to >> do something aweful like this : >> # dd if=3D/boot/zfsboot of=3D/dev/ada0 count=3D1 >> > > That will overwrite the MBR partition table. > > > # sysctl kern.geom.debugflags=3D0x10 >> # dd if=3D/boot/zfsboot of=3D/dev/ada0 skip=3D1 seek=3D1024 >> > > That seems dangerous. I have not tried with zfsboot, but this should be > close: > > # gpart bootcode -b /boot/zfsboot ada0 > # gpart bootcode -b /boot/zfsboot ada0s1 > > Untested! The first one may need to use /boot/mbr. A better way to do > this, provided the system does not have a broken BIOS, would be to backup= , > repartition with GPT, and restore, avoiding the complication of multiple > partitioning schemes.
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