Re: GPT probe: signature vs checksum

[Andrew Clausen]

On Fri, Nov 30, 2001 at 03:00:33PM +1100, Andrew Clausen wrote:
> ANYway... the GPT probing code has the wrong semantics, IMHO.  It
> is checking for a VALID gpt table, when it should merely be searching
> for a gpt table.  It should be checking signatures ONLY.  Not
> checksums.  (And perhaps this 0xEE partition thing).

I should add:

There is a problem, that the signatures aren't enough to guarantee
that you have a partition table (eg: the stale signature problem), and
checksums can be used as a heuristic for making a better decision
(perhaps... I'm yet to be convinced).

So, I propose something like:

int
gpt_probe(...)
{
        if (!sigs_correct)
                return 0;

        if (pmbr_ok) {
                return 1;
        } else {
                ask, default to ok
        }
}

If the checksums are incorrect, then this should not be reason
to believe there is no GPT table, but rather, the table is corrupt,
and would you like to use the backup, sir?

Andrew