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Date: Thu, 4 Nov 2021 10:19:53 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Linux NVDIMM <nvdimm@lists.linux.dev>
Subject: Re: qemu-emulated nfit devices disappeared
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On Thu, Nov 04, 2021 at 10:17:31AM -0700, Christoph Hellwig wrote:
> On Thu, Nov 04, 2021 at 10:09:37AM -0700, Dan Williams wrote:
> > Hmm, so the driver has 2 modes "labeled" and "label-less", in the
> > labeled mode it waits for an explicit:
> > 
> >     ndctl create-namespace
> > 
> > ...to provision region capacity into a namespace. In label-less mode
> > it just assumes that the boundaries of the region are the boundaries
> > of the namespace. In this case it looks like the driver found a label
> > index block with no namespaces defined so it's waiting for one to be
> > created. Are you saying that the only thing you changed from a working
> > config with defined namespace to this one was a kernel change? I.e.
> > the content of those memory-backend files has not changed?
> 
> Well, the config change is the only thing I though of as relevant.
> The content of those files actually changes all the time, as I also
> use them as the backing store for my qemu configs that use block
> devices.  E.g. the previous run they did show up as NVMe devices.

Ok, blowing the files away and recreating them makes the pmem
devices show up again.