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Date: Mon, 27 Nov 2006 18:10:33 +0000
From: Alan <alan@lxorguk.ukuu.org.uk>
To: avl@logic.at
Cc: linux-kernel@vger.kernel.org
Subject: Re: Allow turning off hpa-checking.
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> What else (if not sector remapping) could make the "current"
> size gradually smaller between reboots. And why is "native"
> size still constant?  And why does now even access to the but-last
> native sector fail? The explanation with block-reads no longer
> works.

The presented size of an ATA disk is constant. It keeps additional space
for error blocks. The HPA merely tells the disk to lie about its size.
 
> > This is a matter for the partitioning tool. You don't know at boot time
> > what you wish to do with the HPA so a boot option is inappropriate.
> 
> If I boot linux (e.g. from CD) on some precious windows-machine,
> I do know that at boot time. Ditto if I connect a foreign
> windows-disk in my machine (ata is afaik not yet hot-pluggable),
> I'm also bound to know that at boot time.

Some ATA is hot pluggable. The new libata stuff very much so (although it
at the moment doesn't handle HPA)
 
> There are also user-land tools (using ioctl) to manipulate 
> this, in case I change my mind lateron.
> 
> How should the partitioning tool know, if I want to ignore the
> HPA, or respect it (knowing it contains stuff that I might need in
> future).  Does there exist any that asks me?

I have no idea. If not perhaps one should be written.