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

[Daniel Wagner]

On Wed, Oct 09, 2024 at 03:19:59PM GMT, Matias Bjørling wrote:
> On 09-10-2024 09:46, 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.
> > 
> 
> It's a good point. Damien, Keith, and I were debating it during ALPSS. They
> preferred the "send command and see if it fails" approach over writing
> specific conditions where it would apply. Note that Keith did suggest to
> avoid the command on 1.0 and 1.1 devices, and they were known to fail with
> unsupported CNS ids.

FWIW, there are some devices out there which will log these attempts and
spam their error logs. There were plenty of reports against nvme-cli
when nvme-cli issued a command which could fail.