Re: [PATCH v4 4/4] nvme-pci: Support shared tags across queues for Apple 2018 controllers

[Christoph Hellwig]

On Wed, Aug 07, 2019 at 05:51:22PM +1000, Benjamin Herrenschmidt wrote:
> Another issue with the Apple T2 based 2018 controllers seem to be
> that they blow up (and shut the machine down) if there's a tag
> collision between the IO queue and the Admin queue.
> 
> My suspicion is that they use our tags for their internal tracking
> and don't mix them with the queue id. They also seem to not like
> when tags go beyond the IO queue depth, ie 128 tags.
> 
> This adds a quirk that marks tags 0..31 of the IO queue reserved

What a mess.  But given how widely available the macbooks are supporting
them makes sense:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>