p.lavarre at ieee.org
Fri Aug 13 08:06:53 PDT 2004
This message is from the T13 list server.
>> > Every ATA read/write command specifies
>> > transfer length and data direction already.
>> > No need to store or derive that information elsewhere.
> > Ah, for vendor-reserved commands, yes it would need specification.
> We want SCSI to be a blind tunnel to the ATA device.
> The bridge should not look at
> the command code, sector count, or any other part of the register set.
> This is what makes it work
> for standard and vendor specific ... also ... new commands
Always we should speak of wanting a transparent bridge because
"vendor-specific and newly standard" ops break an opaque bridge, not
just that the "vendor-reserved commands" break an opaque bridge.
Of course, a new data transport will break even a transparent bridge.
We saw this recently, for example, when we added 48-bit LBA's to
USB/ATA bridges that knew only 28-bit LBA's, also when we added UDMA
thruput to USB/ATA bridges that knew only PIO.
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