Re: [RFC][PATCH] GPT Protective MBR changes

[Andrew Clausen]

Hi Matt,

Sorry, I forgot to answer this.  (I need to learn to use Mutt properly...)

On Fri, Sep 28, 2001 at 03:51:04PM -0500, address@hidden wrote:
> Now, Intel wants to change this.  They want the Protective MBR (PMBR) to be
> required also.  If something zeros or otherwise changes the PMBR, then
> *those* changes should take effect, and the disk is no longer considered
> GPT.

Actually, this is probably a wise thing to do, because there will be a
tonne of partition programs who know nothing about GPT.  If users want to
"convert back" with their old tools, they wouldn't have been able to
(they wouldn't have known they needed to clobber everything)

> I don't like this at all.  Essentially, the Alternate GPT stuff becomes
> useless.  How often will blocks 1-33 be changed when block 0 isn't?

Is that the issue?  If block 0 changes, then that means 1-33 are possibly
being ignored, etc.

> In any case, I've made a patch to parted-1.4.19-pre4 at
> http://domsch.com/linux/parted/parted-1.4.19-pre4-gpt-20010928.patch which
> implements this change, but asks the user what they think the right thing to
> do is.

Yep, I like it :)

> If it comes across a case where there exists valid GPT info, but no PMBR, it
> asks.
> Yes means the disk is still GPT, just re-write the PMBR.
> No means the disk is now considered MBR, and erase any valid GPT info.
> Ignore means the disk is now considered MBR, but don't write to it.

Makes sense.

Thanks!
Andrew