[sane-devel] help with scsi questions??

[paul beard]

[sane-devel list cc:ed]

I'm working with the SANE folks to figure out why the scsi scanner
on my 9500's external bus is so flaky. We have worked through some
compiler issues (too much optimization was causing values to get
munged) and some patches to how SANE probes the scanner itself.

The scanner can be identified and almost works: still no image 
acquisition and we're seeing some bus resets while scan commands 
are being sent, which hoses things up.

Now we're down to this: can anyone clarify?

 > So it seems that there are a few issues with the SCSI system
 > of your machine.
 >
 > A more general SCSI question: (I assume that the folks who
 > adapted NetBSD to the Apple hardware know this, but let us be
 > sure ;) The reason that Apple installs two SCSI busses in
 > many of their computers is to have a fast internal bus for
 > the hard disks; this bus needs the usual careful setup:
 > proper cabling and termination; for the external bus Apple
 > managed to design the interface in an amazing
 > "error-friendly" way. I have seen several absolutely wrong
 > setups working flawlessly, like a 1.5 m cable at the end of
 > the bus without a device and without a terminator. This can
 > only work for slow transfer speeds, so I wonder if the NetBSD
 > kernel really ensures that the speed of the external bus is
 > really 5 MHz. Do you see anything related messages with dmesg
 > or in some log files?