linux-kernel - Re: completely hide parts of the partition table from Windows?

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Message-ID: <20090818223522.GA5872@ub>
Date:	Wed, 19 Aug 2009 00:35:23 +0200
From:	"Andries E. Brouwer" <Andries.Brouwer@....nl>
To:	Mikael Pettersson <mikpe@...uu.se>
Cc:	linux-kernel@...r.kernel.org,
	Andries Brouwer <Andries.Brouwer@....nl>
Subject: Re: completely hide parts of the partition table from Windows?

On Tue, Aug 18, 2009 at 11:22:30PM +0200, Mikael Pettersson wrote:

> So what I'm looking for is some sub-partition table format with the
> following two properties:
> 1. resides in an msdos partition entry of a type that Windows does
>    not inspect (for whatever extended partitions or Apple/BSD/Sun
>    stuff that Windows may have been taught to recognize)
> 2. the locations and sizes of the sub-partitions are NOT limited by
>    the parent msdos partition entry

The reason I added type 85 = LINUX_EXTENDED_PARTITION
was precisely your concern: it should be something
that DOS/Windows doesnt know about.

> I've looked at the code in fs/partitions/msdos.c, and it seems that
> most of the extended/BSD/Sun formats don't give me property #2 above.

The standard description of extended partitions says that the size field
of the parent extended partition descriptor is irrelevant, only the
starting sector matters.

If you look at the parse_extended() code in msdos.c you'll see
that it does not use its parameter first_size.
(Except in a certain case that you will not be in.)

Make a table that has a Linux extended partition (type 85)
that is short enough not to cause Windows to worry. Have logical
partitions inside of any size and location you desire.

Andries

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