Re: [PATCH] nested partitions

[Vladimir 'phcoder' Serbinenko]

Rediff
On Mon, Aug 17, 2009 at 4:34 PM, Vladimir 'phcoder'
Serbinenko<address@hidden> wrote:
> On Mon, Aug 17, 2009 at 4:06 PM, Robert Millan<address@hidden> wrote:
>> On Mon, Aug 17, 2009 at 03:00:52PM +0200, Vladimir 'phcoder' Serbinenko 
>> wrote:
>>> Rediff and few fixes
>>
>> Please note that after what we discussed on IRC, we need to find a solution
>> that wouldn't make boot time increase linearly with the number of filesystems
>> or partmaps GRUB supports.
>>
> It probe time scales linearly no matter what we do. Fortunately with
> disk cache few first sectors are read and checked for different
> signatures which is fast. As for module autoload with search patch it
> doesn't happen except in the failure to access requested device.
>> I really think supporting every sort of combination is too extreme.  For
>> example who would want an msdos/msdos chain?  OpenSolaris creates one, but
>> it's a false positive.
>>
> minix does it and it's not a false positive.
>> The overall idea *is* nice.  Some combinations (e.g. msdos/bsd) are cleaner
>> this way, but supporting everything doesn't scale well.
> AFAIK no partmap goes beyond first 16K for signature checking. Time
> for signature checking can be neglected and 16K would be read for
> filesystem probe too. Additionally e.g. (hd0,1) is probed for
> subpartitions only if (hd0,1,X) is requested or we're scanning through
> partitions. In last case we're likely to fsprobe partition anyway so
> it doesn't create any overhead
>>
>> Perhaps we can explicitly list which combinations make sense?  So when an
>> msdos label is found, its partitions are probed for bsd labels too, but not
>> for msdos labels again, etc.
>>
>> --
>> Robert Millan
>>
>>  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
>>  how) you may access your data; but nobody's threatening your freedom: we
>>  still allow you to remove your data and not access it at all."
>>
>>
>> _______________________________________________
>> Grub-devel mailing list
>> address@hidden
>> http://lists.gnu.org/mailman/listinfo/grub-devel
>>
>
>
>
> --
> Regards
> Vladimir 'phcoder' Serbinenko
>
> Personal git repository: http://repo.or.cz/w/grub2/phcoder.git
>



-- 
Regards
Vladimir 'phcoder' Serbinenko

Personal git repository: http://repo.or.cz/w/grub2/phcoder.git

nestpart.diff
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