De facto, best as I mis/remember, Windows ME/ 98/ 95 asked often for
x0E (14) bytes and Win XP/ 2K/ NT now asks often for x12 (18) bytes.
Furthermore, Windows ignores the additional length byte.
Consequently, naturally, yes, because of the rudeness of those many
hosts, now many commodity peripheral storage devices choke over a
request for anything other than x12 (18) bytes, and give the host
zero or other noise in the additional sense byte.
...
Soon enough we'll see if the next new de facto requested sense
data length is x10, clashing with SAT passthru, x14 for 32-bit
alignment, or x18 to satisfy 64-bit alignment and SAT passthru...
FYI when doing the equivalent of SG_IO on Windows to the same
bridge, we
can get back all 22 sense bytes by specifying that in the passthru
structure. So while Windows may internally only want to deal with
specific sizes, when user-space asks for a size, it seems to obey it.
:) Give it time.
I'm guessing in Windows you mean the auto sense of DeviceIoControl
SCSI_PASS_THROUGH_DIRECT, analogous to such Linux ioctl's as
CDROM_SEND_PACKET & SG_IO.
I agree your mileage probably won't vary until you find a Unix, a
PCI/ USB bridge, another bus, whatever, that imposes different
alignment or length constraints on sense data, for which these new
x16-byte-sense SAT passthru conventions are a surprise.
Thanks again for sharing your episode of pain so fully.
Me, I remember Windows Atapi rounding up misaligned lengths into
unallocated memory, Windows FireWire truncating to a max, and Windows
FireWire rejecting "unsolicited sense" (i.e., SCSI op x03 Request
Sense not preceded by a Check Condition), all interfering with the
transparent pass thru of more than ordinary sense data, despite the
irrefutable theory that all hosts should request xFF bytes and
gracefully settle for less.
Could be, provided you only support the newest Windows & Linux, then
exploiting variability in SCSI sense length might even work, this
time around. Soon enough, we'll see ...
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