Re: [PATCH 1/2] nvme: make independent ns identify default

[Keith Busch <kbusch@kernel.org>]

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.

We have other quirks for disabling specific identifications (ex:
nvme_ctrl_limited_cns, NVME_QUIRK_NO_NS_DESC_LIST) in case something
really break certain identifies. But I think anything >= 1.3 should be
fine: the CNS handling is well defined from that point onward, so we
shouldn't make anything harder than necessary from assuming someone got
identication this wrong.

The only pain I can think of is that some controllers increment their
error log count, and SMART tools creates unnecessary alerts for that.