Re: [PATCH] Re: Multiple partition maps

[phcoder <phcoder@gmail.com>]

Robert Millan wrote:
> On Tue, Sep 09, 2008 at 02:47:11AM +0200, phcoder wrote:
>> Robert Millan wrote:
>>> On Mon, Sep 08, 2008 at 08:27:05PM +0200, phcoder wrote:
>>>> Robert Millan wrote:
>>>>> On Thu, Sep 04, 2008 at 11:54:43PM +0200, phcoder wrote:
>>>>>> BTW GPT module checks the protective MBR. In some cases when legay OS
>>>>>> modified the MBR it's no longer "protective MBR". And in theese cases
>>>>>> GRUB will refuse to boot. Isn't the magic number check enough?
>>>>> If there's at least one protective GPT partition (0xee), I think this should
>>>>> be considered enough to accept the partmap as GPT.
>>>>>
>>>> In GPT module if first partition is not of type 0xee then it's
>>>> considered that no GPT is present. Is think that this check is
>>>> error-prone (with e.g. bootcamp) and unnecessary
>>> Agreed.  Can you fix this?
>>>
>> I send a patch for it. However I couldn't test it because of the bug in
>> the make system. About the bug I'll post in appropriate thread. In that
>> patch the pc module explicitely checks for the absence of GPT table. IMO
>> it's ugly. Another alternative would be to assign priorities to the
>> partition tables. I also tried this way and send patch for it. Again I
>> couldn't test it.
> 
> This patch looks overly complicated.  Fixing the discussed problem ought
> to be much simpler...
> 
>> -  /* Make sure the MBR is a protective MBR and not a normal MBR.  */
>> -  if (mbr.entries[0].type != GRUB_PC_PARTITION_TYPE_GPT_DISK)
>> -    return grub_error (GRUB_ERR_BAD_PART_TABLE, "no GPT partition map found");
> 
> ... here, it'd be just a matter of replacing this hardcoded '0' with an
> iterator.
> 
> And maybe something similar for partmap/pc.c.
> 
I don't think that this is enough since with bootcamp you can have a MBR
 without a protective entry. This leaves us with just two option:
priorities and ugly check in partmap/pc.c. I would prefer the first one
since the second one is unextensible. With first one I'll be able to do
something similar to what you can find in other bootmanagers: ability to
have more then one "primary" partition (like in http://symon.ru ).
Vladimir 'phcoder' Serbinenko