Re: [PATCH] nvme: determine the number of IO queues

[Minwoo Im <minwoo.im.dev@gmail.com>]

On 4/18/19 9:52 PM, Aaron Ma wrote:
> 
> 
> On 4/18/19 8:13 PM, Minwoo Im wrote:
>>> Yes the IO queues number is 0's based, but driver would return error and
>>> remove the nvme device as dead.
>>
>> IMHO, if a controller indicates an error with this set_feature command,
>> then
>> we need to figure out why the controller was returning the error to host.
>>
>> If you really want to use at least a single queue to see an alive I/O
>> queue,
>> controller should not return the error because as you mentioned above,
>> NCQA, NSQA will be returned as 0-based.  If an error is there, that could
>> mean that controller may not able to provide even a single queue for I/O.
> 
> I was thinking about try to set 1 I/O queue in driver to try to probe
> NVME device.
> If it works, at least system can bootup to debug instead of just remove
> NVME device and kernel boot hang at loading rootfs.

If the controller returns error for that command, how can we assure that
the controller would support a single I/O queue ?

> 
> If you still concern this 1 I/O queue I can still set it as
> *count = 0;
> 
> At least we try all count, NVME device still failed to respond.
> 
> Regards,
> Aaron
> 
>>
>> Thanks,
>> Minwoo Im