Garbage in, surprises out. Have things changed? Well as
I found out recently this is a relatively complex question
in the case of the linux scsi sub-system. The answer
depends on which of the 2 error processing regimes
available that your adapter driver uses.
If the newer regime is used ("eh_code") then the request
by the sg driver for no retries is almost always honoured.
So there shouldn't be any retries, resets, etc
If the older regime is used then the situation described
above occurs. [If the ".h" or the ".c" file of your
adapter source contains something like:
use_new_eh_code: 1
then this is the newer regime. If not, it is using the older
regime.]
Unfortunately, a large majority of linux scsi adapter drivers
(including aic7xxx) use the older regime. The maintainer of
the scsi mid level, Eric Youngdale, has renewed his push
for the adapter driver maintainers to upgrade to the newer
regime. The nature of open software development makes it
difficult to force such an issue too hard but things are
changing slowly.
Sorry the answer couldn't be a bit more positive.
On a brighter note, the 2.3 linux kernel developmemt tree
contains a usb_scsi pseudo adapter driver. This opens
up the possibility of using SANE on USB scanners that
uses a scsi command set. Does anyone know of USB scanner
models that use a scsi command set? [Oliver Rauch told me
yesterday that he thinks the Umax 2200 falls into this
group.]
Doug Gilbert
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