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Date: Tue, 17 Apr 2018 19:34:59 -0400
From: "Theodore Y. Ts'o" <tytso@mit.edu>
Subject: Re: ioctl FIBMAP for dax gone in v4.17-rc1
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To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Andreas Dilger <adilger@dilger.ca>, Dan Williams <dan.j.williams@intel.com>, Christoph Hellwig <hch@infradead.org>, Xiong Zhou <xzhou@redhat.com>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, linux-xfs <linux-xfs@vger.kernel.org>, Eric Sandeen <sandeen@sandeen.net>, fstests <fstests@vger.kernel.org>, linux-nvdimm <linux-nvdimm@lists.01.org>

On Tue, Apr 17, 2018 at 10:50:07AM -0700, Darrick J. Wong wrote:
> syslinux does FIEMAP w/ FIBMAP fallback.
> 
> lilo & elilo still use FIBMAP only, but lilo hasn't seen a release since
> 2015 and elilo 2013.  I prefer not to add FIBMAP support in XFS-DAX for
> the singular case of booting off pmem via lilo.

It shouldn't be that hard to write a userspace emulation layer which
exports a FIBMAP-like functional interface but gets the information
from the kernel using the FIMAP ioctl....

					- Ted