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Date:   Thu, 1 Nov 2018 20:31:30 -0300
From:   Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
To:     Christoph Hellwig <hch@lst.de>
Cc:     linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        Sagi Grimberg <sagi@grimberg.me>, Jens Axboe <axboe@fb.com>,
        Potnuri Bharat Teja <bharat@chelsio.com>,
        Keith Busch <keith.busch@intel.com>,
        Hannes Reinecke <hare@suse.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>
Subject: Re: [PATCH] nvme: create 'paths' entries for hidden controllers
Message-ID: <20181101233129.GB4249@calabresa>
References: <20180928191720.3461-1-cascardo@canonical.com>
 <20181005073245.GA24224@lst.de>
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On Fri, Oct 05, 2018 at 09:32:45AM +0200, Christoph Hellwig wrote:
> On Fri, Sep 28, 2018 at 04:17:20PM -0300, Thadeu Lima de Souza Cascardo wrote:
> > When using initramfs-tools with only the necessary dependencies to mount
> > the root filesystem, it will fail to include nvme drivers for a root on a
> > multipath nvme. That happens because the slaves relationship is not
> > present.
> > 
> > As discussed in [1], using slaves will break lsblk, because the slaves are
> > hidden from userspace, that is, they have no real block device, just an
> > entry under sysfs.
> > 
> > Introducing the paths subdir and using that on initramfs-tools makes it
> > possible to now boot a system with nvme multipath as root.
> 
> Do we need documentation how these paths links are supposed to work?
> Who is going to parse them?

Hi, Christoph.

I have just sent a v2 against block/for-next with a Documentation file
describing it. The first intended user is initramfs-tools, documented there as
well.

Thanks.
Cascardo.