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.
If making the check conditional, I think checking if the device follows
2.0 specification isn't sufficient, as some devices may implement a
subset of the 2.0 features (for example the independent ns data struct),
while reporting as a 1.4 device.
Is there maybe better way, that isn't dependent on some feature being
implemented (such as CRIMS capability)?
