Re: Sending ATA commands?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> [...], I wonder if you could attach the HPA area as an additional
> partition on the default disklabel, or, if the disk is gpt
> partitioned, fake up another partition in the gpt table.

I don't see any reason why not.  I'm not sure whether you're proposing
that the HPA not be accessible any other way or whether this is just a
default.

> In any case, I think I would be most comfortable with an
> implementation which set the HPA area as read-only and only became
> read-write through some user command, perhaps a new command for
> atactl(8).

That strikes me as a reasonably sensible idea.  I'm not sure whether
I'd want it to be tacked onto the end of the drive or not (eg, for
access through RAW_PART) - I don't like having even one partition with
magic semantics and really don't want to add another, but I'm not sure
how else to do this.

> I realize that from a hardware perspective, you may not be able to
> set read-only on the HPA once you enable access to it, but I imagine
> you could set that restriction in the wd(4) driver.

As I understand it, yes, this, would have to be a NetBSD-imposed
limitation.  I saw nothing in the doc that makes me think there's any
way to enable read but not write access to the HPA.

> Have you found any BIOS's that can use this HPA area to load saved
> NetBSD rescue images as a way of restoring machines [whose] disks
> have been corrupted?

No, but I haven't looked, either.  I have no idea what would need to be
in an HPA in order for an HPA-aware BIOS to do anything useful with it;
at a stab-in-the-dark guess, I'd guess that it would depend heavily on
the particular BIOS in question - which at that point I'm no longer
sure deserves the B part of the name.

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