On Mon, Jun 20, 2022 at 08:24:24AM +0200, Hannes Reinecke wrote: > So my idea for SATA is simply _not_ to use reserved tags. > Any TMF functions (or the equivalent thereof) should always be sent as > non-NCQ commands. And when doing so we're back to QD=1 on SATA anyway, so > there _must_ be tags available. Consequently the main reason for having > reserved tags (namely to guarantee that tags are available for TMF) doesn't > apply here. At least in the non-elevator case (which includes all passthrough I/O) request have tags assigned as soon as they are allocated. So, we absolutely can have all tags allocated and then need to do a TMF.