Re: [Gptfdisk-general] Support reverting a hybrid MBR configuration

[Rod S. <rod...@ro...>]

On 10/02/2017 12:44 AM, 林博仁 wrote:
> (NOTE: I'm not subscribed to this list, please CC me.)
> 
> Hello.  I would like to request a feature to revert a previously
> configured Hybrid MBR configuration as I like to avoid any *surprises*
> during installing Windows.

It's not clear to me precisely what you mean; however, gdisk might
already do what you want:

* You can replace a hybrid MBR with a legal protective MBR by using the
  "n" option on the experts' menu.
* You can create a new hybrid MBR by using the "h" option on the
  recovery & transformation menu.
* You can abort from most operations without writing changes to disk
  by selecting "q" in any menu.
* You can back up all partition table data by using the "b" option on
  the main menu, and restore a backup by using the "l" option on the
  recovery & transformation menu.

It's impossible to return to a previous state once the partition table
has been written unless a backup has been saved. Making such recovery
possible would require automatically writing backups to some directory,
and of course the recovery would only work if gdisk were the only
program used to partition the disk.

It's impossible to guarantee no "surprises" when installing Windows (or
any other OS). I strongly recommend you read up on the differences
between BIOS-mode and EFI-mode installations and learn how to control
the boot mode your computer uses to boot an OS installation medium. My
page on the CSM may be helpful:

http://www.rodsbooks.com/efi-bootloaders/csm-good-bad-ugly.html

Note that this page is written mainly for UEFI-based PCs. Macs differ in
some important details, although the basic principles are the same.

-- 
Rod Smith
rod...@ro...
http://www.rodsbooks.com