Re: Reliability of RPC services

[Jonathan S. Shapiro]

On Wed, 2006-04-26 at 19:32 -0500, Jesse D. McDonald wrote:
> On Wednesday 26 April 2006 19:17, Jonathan S. Shapiro wrote:
> > On Wed, 2006-04-26 at 19:05 -0500, Jesse D. McDonald wrote:
> > > This appears to be the primary point of contention for at least one
> > > version of this thread, but the resolution is simple. In no case would an
> > > untrusted device driver loaded by the user be granted free access to
> > > either the PCI bus (or any device thereon, given their DMA capabilities)
> > > or the system I/O space.
> >
> > Good. Then we are done, because this is basically the universal set of
> > all devices.
> 
> It's actually a fairly limited set of devices. It doesn't include, for 
> example, USB or IEEE-1394 devices (even if they happen to be accessed through 
> a PCI controller), or (probably) ATA devices (it depends on the ATA 
> protocol).

Jesse:

If you believe that, you need to go read the respective specifications
more carefully. USB and IEEE-1394 *definitely* allow remote devices to
be masters. ATA is more SCSI-like every day. I haven't checked, but I
bet that ATA allows it too. In fact, I'm pretty sure I remember
disconnected operations in ATA-6, which amounts to the same thing.

shap