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Date: Thu, 10 Oct 2024 09:53:51 +0200
From: Christoph Hellwig <hch@lst.de>
To: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Matias =?iso-8859-1?Q?Bj=F8rling?= <m@bjorling.me>,
	dlemoal@kernel.org, cassel@kernel.org,
	linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Matias =?iso-8859-1?Q?Bj=F8rling?= <matias.bjorling@wdc.com>
Subject: Re: [PATCH 1/2] nvme: make independent ns identify default
Message-ID: <20241010075351.GA7525@lst.de>
References: <20241008145503.987195-1-m@bjorling.me> <20241008145503.987195-2-m@bjorling.me> <20241009074611.GB16181@lst.de> <ZwaZoJayzu6XZom1@kbusch-mbp>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Wed, Oct 09, 2024 at 08:56:32AM -0600, Keith Busch wrote:
> On Wed, Oct 09, 2024 at 09:46:11AM +0200, Christoph Hellwig wrote:
> > On Tue, Oct 08, 2024 at 04:55:02PM +0200, Matias Bjørling wrote:
> > > However, the independent namespace data structure
> > > is mandatory for devices that implement features from the 2.0+
> > > specification. Therefore, we can check this data structure first. If
> > > unavailable, retrieve the generic attributes from the NVM command set
> > > identify namespace data structure.
> > 
> > I'm not a huge fan of this.  For pre-2.0 controllers this means
> > we'll now send a command that will fail most of them time.  And for
> > all the cheap low-end consumer device I'm actually worried that they'll
> > get it wrong and break something.
> 
> We already send identify commands that we expect may break on pre-2.0
> controllers: the Identify NS Descriptor List.

Identify NS Descriptor List is mandatory starting with NVMe 1.3.  We only
issue it for 1.3 or if the controller advertises supporting multiple
command sets.