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> 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
Ouch, yes.
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.
Pat LaVarre
