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Re: pass-through linux ioctl for mfi(4)

On Sun, Sep 16, 2012 at 06:12:19PM -0400, Thor Lancelot Simon wrote:
> > Yes, of course it's a risk. We support a similar ioctl for other drivers,
> > e.g. amr(4). the pass-through for scsi(4) and ata(4) devices could
> > probably do something similar too.
> The scsi and ata case is very different, because we have enough
> documentation to allow us to parse the commands, and perform at least
> some kind of access control -- even if we do not do so in all cases in
> which we could.
> The case of amr and mfi is very different: as far as I know, there is
> no documentation whatsoever of the command format between megacli and
> the card firmware, so we cannot, for example, allow hot-plugging or
> even battery status checks without allowing overwriting arbitrary disk
> blocks.  Ugly, ugly, ugly.

Of course closed hardware is ugly, and I'd very much prefer to work on
hardware for which I have docs, instead of reverse-engineering.
But we have to live with it, unfortunably.

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference

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