[Gllug] Letting Bohcs, UML or vmware have direct access to a PCI card or a SCSI device (not disk).

[Nix]

On Fri, 16 Sep 2005, Ian Norton-Badrul announced authoritatively:
> On Thu, Sep 15, 2005 at 01:42:12PM +0100, Nix wrote:
>> I hope that direct access to a SCSI device isn't possible, because given
>> that it's quite easy to access *any* SCSI device on the bus, and also to
>> completely violate system security (think `command a DMA into kernel
>> memory').
> 
> AFAIK Direct scsi access to a device is possible if you put another
> controller on the bus (bus arbitration), im talking to synchronous scsi
> hardware so there would be no issues as with sharing a disk for
> example.

As long as it can't do anything like DMA (to be more precise, as long as
it can't do bulk transfers to user-specified addresses in main system
memory, avoiding the CPU), you're safe. But if it can't do DMA, it's
probably *slow*.

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