FreeBSD 10.0-RC3 Now Available
Warren Block
wblock at wonkity.com
Fri Dec 27 16:08:11 UTC 2013
On Fri, 27 Dec 2013, Mathieu Arnold wrote:
> +--On 27 décembre 2013 10:28:07 -0500 Thomas Hoffmann <trh411 at gmail.com>
> wrote:
> | All the examples I've seen for updating bootcode assume GPT. If one has
> | MBR (as I do) and assuming the following basic scheme:
> |
> | gpart show ada0
> | => 63 976773105 ada0 MBR (466G)
> | 63 976773105 1 freebsd [active] (466G)
> |
> | gpart show ada0s1
> | => 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) and
> | 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
bootcode correctly.
> you have to
> do something aweful like this :
> # dd if=/boot/zfsboot of=/dev/ada0 count=1
That will overwrite the MBR partition table.
> # sysctl kern.geom.debugflags=0x10
> # dd if=/boot/zfsboot of=/dev/ada0 skip=1 seek=1024
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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