On 10-10-2024 16:47, Daniel Wagner wrote:
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.
Got it. So, given the feedback from you, Keith, and Christoph. It's safe
to say it needs to be a conditional check.
Would anyone object if the
if ((ctrl->cap & NVME_CAP_CRMS_CRIMS) ||
(info.ids.csi != NVME_CSI_NVM && info.ids.csi != NVME_CSI_ZNS))
statement would include a check for endurance group support?
The idea being that it's mandatory for a device to implement an
endurance group in case it exposes the rotational flag. That check would
limit the failed command check to relatively new devices.
