8.0-RELEASE / gpart / GPT / marking a partition as "active"

[Mike Andrews]

On 1/19/10 4:09 PM, Dan Naumov wrote:
> On 1/19/2010 12:11 PM, Dan Naumov wrote:
>> It seems that quite a few BIOSes have serious issues booting off disks
>> using GPT partitioning when no partition present is marked as
>> "active". See http://www.freebsd.org/cgi/query-pr.cgi?pr=115406&cat=bin
>> for a prime example.
>>
>> In 8.0-RELEASE, using gpart, setting a slice as "active" in MBR
>> partitioning mode is trivial, ie:
>>
>> gpart set -a active -i 1 DISKNAME
>>
>> However, trying to do the same thing with GPT partitioning yields no results:
>>
>> gpart set -a active -i 1 DISKNAME
>> gpart: attrib 'active': Device not configured
>>
>> As a result of this issue, I can configure and make a succesfull
>> install using GPT in 8.0, but I cannot boot off it using my Intel
>> D945GCLF2 board.
>>
>> I have found this discussion from about a month ago:
>> http://www.mail-archive.com/freebsd-stable@freebsd.org/msg106918.html
>> where Robert mentions that "gpart set -a active -i 1" is no longer
>> needed in 8-STABLE, because the pmbr will be marked as active during
>> the installation of the bootcode. Is there anything I can do to
>> archieve the same result in 8.0-RELEASE or is installing from a
>> snapshop of 8-STABLE my only option?
>
>> After using gpart to create the GPT (and thus the PMBR and its
>> bootcode), why not simply use "fdisk -a -1 DISKNAME" to set the PMBR
>> partition active?
>
> According to the fdisk output, the partition flag did change from 0 to
> 80. Can the "fdisk: Class not found" error showing up at the very end
> of the procedure of doing "fdisk -a -1 DISKNAME" be safely ignored?

Yes, just ignore it.