[EMAIL PROTECTED] said:
> Can anyone tell me if there are or are not any hardware or firmware
> issues making this impossible?
That depends on the chipset in the bus adapter and the way the adapter is
wired. By and large, most modern chipsets will act as a target (I can only
say this for certain for the symbios 53cxxx scripts chips, although I believe
the aic7xxx sequencer is also target capable), but some older ones won't.
[EMAIL PROTECTED] said:
> Also, would I have to modify the low level driver for the scsi-card,
> or would a patch to the mid level layer be enough to support this in
> the kernel?
Most certainly you'll have to modify the low level. Almost all low level
drivers are designed to drive the bus as an initiator, not as a target. You
would need, at the very least, to add a selection routine to process the
subset of SCSI commands you intend to respond to. There are other subtleties
too: Initiators don't drive the SCSI phase lines, they just respond to
changes in them. As a target, you must drive these lines to take the other
initiator through the bus phases.
You will have to modify the mid-layer as well. Initially, I'd write a separate target
layer and just persuade the mid-layer not to attach to your device. I'd then
integrate the target layer into the mid-layer later on.
Before you do any of this, you might like to poke around a bit. There are rumours
that embedded device manufacturers are interested in Linux as a storage array
controller OS. To get this to work, they'd essentially have to have done what you're
proposing.
James Bottomley
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