patch for ATAng bug

[Soren Schmidt]

It seems David Gilbert wrote:
> Soren> Uhm, I'm working on finding the real problem, and I'd like that
> Soren> to be the solution. However the above may be a good workaround
> Soren> for those bitten by this...
> 
> Well... is it not possible for malicious hardware to claim to have
> zero blocks (by claiming one of it's parameters is zero)?  Obviously
> it is now.  Some of the other crashing complaints (complaints of
> crashing only without media in a zip drive, for instance) seem
> similar.

Hmm, well I dont know of any "malicious hardware" masqurading as
ATA disks actually, but that is a point to consider. The ZIP is
not an ATA device and doesn't panic the atapi-fd driver neither
with nor without a media inserted...

> I agree that the real problem in my instance is that the phantom drive
> shows up.  If I can be any help on that issue, I'd be happy to boot
> test code.

I've committed code that shoudl fix some of there phantom drives..

> But my question is: would the same parameters passed to ad_print()
> result from a pathalogical device (a broken compact flash, hard disk
> or whathaveyou)?  I put the fix in ad_attach() because I felt that
> some other code might break ... but shouldn't we at least protect the
> divide-by-zero ... or better reject devices of size zero at this
> point.  I can't imagine that zero sizes devices are very useful for
> storing things.

I've newer seen or heard about an ATA device with a zero size, so I
think its a bit academic, but I'll keep it in mind..

-Søren