svn commit: r292057 - in head/sys: boot/common geom/part

[John Baldwin]

On Thursday, December 10, 2015 10:35:07 AM Andrey V. Elsukov wrote:
> Author: ae
> Date: Thu Dec 10 10:35:07 2015
> New Revision: 292057
> URL: https://svnweb.freebsd.org/changeset/base/292057
> 
> Log:
>   Make detection of GPT a bit more reliable.
>   
>   When we are detecting a partition table and didn't find PMBR, try to
>   read backup GPT header from the last sector and if it is correct,
>   assume that we have GPT.

One thing that your commit message did not make clear:

Does this only detect as valid if no other partition scheme claims the
disk?  That is, if I overwrite a previously GPT-partitioned disk with a
different scheme (e.g. MBR), will that disk now probe as GPT instead of
the new scheme?  If so, this is broken and needs to be reverted.  If this
somehow does a "low" priority probe and only kicks in if no other scheme
claims the disk, then this is ok, but you should probably have said so in
the commit message.

-- 
John Baldwin