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Date:      Sat, 26 Jan 2002 20:34:19 -0800
From:      Terry Lambert <tlambert2@mindspring.com>
To:        David Schultz <dschultz@uclink.berkeley.edu>
Cc:        "Gary W. Swearingen" <swear@blarg.net>, freebsd-chat@FreeBSD.ORG
Subject:   Re: Why dual boot?
Message-ID:  <3C53834B.840839A2@mindspring.com>
References:  <20020123223104.SM01952@there> <3C4FBE5C.2AE8C65@mindspring.com> <4.3.2.7.2.20020124213809.00e6e5d0@localhost> <20020125131659.GB7374@hades.hell.gr> <3C51CD33.4E69B204@mindspring.com> <001b01c1a635$636a4170$0a00000a@atkielski.com> <20020126003431.A77505@HAL9000.wox.org> <y4wuy46bza.uy4@localhost.localdomain> <20020126164014.B810@HAL9000.wox.org> <3C5353D2.ACC62BD@mindspring.com> <20020126194349.A1641@HAL9000.wox.org>

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David Schultz wrote:
> > Yes.  Plus it could not really be safely read/write, unless
> > you mapped out the sectors in one large file, and only
> > modified them after getting their location from the NTFS.
> >
> > There is currently no capability for getting the file sector
> > list for a file, within FreeBSD (interestingly, Windows has
> > the ability to do this, as an OS service).
> 
> I'm not claiming this would be efficient or safe, but couldn't you
> just map an NTFS file to memory and steal the rest of the code from
> mfs?

No such thing as a "putpages" or a block write strategy
routine for NTFS.  It's not writable, remember?

The only way you could do it would be to get the block
list from the file and access it directly by block offset
from the device.

The missing pieces for this are: (1) PHK killed block
devices, and you basically need two devices worth of
access to the one disk simultaneously, and (2) there's
no mechanism for returning the block list for a file.

You could maybe get arouns these by writing enough of
an NTFS to open the device (but then you could not mount
it, too) and then use that block list as a device (you
would need a pseudo device driver to do that, which you
would need to write).

Ah... packing workaround on workaround on workaround,
just to avoid doing the right thing... 8-).

-- Terry

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