From mboxrd@z Thu Jan 1 00:00:00 1970 From: keith.busch@intel.com (Keith Busch) Date: Wed, 28 Feb 2018 09:35:11 -0700 Subject: [RFC PATCH] nvme-pci: Bounce buffer for interleaved metadata In-Reply-To: References: <20180224000547.7252-1-keith.busch@intel.com> Message-ID: <20180228163510.GC16002@localhost.localdomain> On Tue, Feb 27, 2018@10:42:27PM -0500, Martin K. Petersen wrote: > > On the other hand, I get the impression some people requesting this > > may think their application will get to access the extended LBAs. The > > reality is the kernel owns the metadata, so I may just setting myself > > up to explain why "fdisk" still shows a 512b format instead of 520b... > > The whole point of DIF (over using regular 520 or 528 byte sectors) was > to keep the logical block size at 512 and not deal with the PI in the > data buffers. > > And the point of defining DIX was to avoid having to do what your patch > is doing. Right, this RFC is just about enabling formats that don't subscribe to the DIX format. It turns out some people believe those extended LBAs are useful for something. I still think this LBA format is not a good fit for this driver, but I'd like to not push people to use out-of-tree or user space drivers if there is a reasonable way to accommodate here. The driver's existing NVMe IO passthrough makes this format reachable already, but there is resistance to use the ioctl over more standard read/write paths.