Re: [PATCHv3 3/5] nvme: implement I/O Command Sets Command Set support

From: Keith Busch <kbusch@kernel.org>
To: Niklas Cassel <Niklas.Cassel@wdc.com>
Cc: "Hannes Reinecke" <hare@suse.de>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"hch@lst.de" <hch@lst.de>, "sagi@grimberg.me" <sagi@grimberg.me>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"Javier González" <javier.gonz@samsung.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"Johannes Thumshirn" <Johannes.Thumshirn@wdc.com>,
	"Matias Bjorling" <Matias.Bjorling@wdc.com>,
	"Daniel Wagner" <dwagner@suse.de>
Subject: Re: [PATCHv3 3/5] nvme: implement I/O Command Sets Command Set support
Date: Tue, 23 Jun 2020 07:25:03 -0700	[thread overview]
Message-ID: <20200623142503.GA1288900@dhcp-10-100-145-180.wdl.wdc.com> (raw)
In-Reply-To: <20200623092033.GA117742@localhost.localdomain>

On Tue, Jun 23, 2020 at 09:20:35AM +0000, Niklas Cassel wrote:
> On Tue, Jun 23, 2020 at 08:20:23AM +0200, Hannes Reinecke wrote:
> > On 6/22/20 6:25 PM, Keith Busch wrote:
> > > From: Niklas Cassel <niklas.cassel@wdc.com>
> > > -	if (ctrl->vs >= NVME_VS(1, 3, 0))
> > > +	if (ctrl->vs >= NVME_VS(1, 3, 0) || nvme_multi_css(ctrl))
> > >   		return nvme_identify_ns_descs(ctrl, nsid, ids);
> > >   	return 0;
> > >   }
> > 
> > Hmm? Are command sets even defined for something earlier than 1.3?
> 
> According to Keith, usually new features are not really tied to a
> specific NVMe version.

Not really according to me; nvme just allows controllers to implement
features ratified after the initial version release.

> So if someone implements/enables multiple command sets feature on
> an older base spec of NVMe, we still want to support/allow that.

Right. We don't check the version to see if multi-command sets are
supported when we initially enable it, so we shouldn't need to check the
version later.