On Thu, Nov 4, 2021 at 10:36 AM Christoph Hellwig <hch@xxxxxx> wrote: > > On Thu, Nov 04, 2021 at 10:34:17AM -0700, Darrick J. Wong wrote: > > /me wonders, are block devices going away? Will mkfs.xfs have to learn > > how to talk to certain chardevs? I guess jffs2 and others already do > > that kind of thing... but I suppose I can wait for the real draft to > > show up to ramble further. ;) > > Right now I've mostly been looking into the kernel side. An no, I > do not expect /dev/pmem* to go away as you'll still need it for a > not DAX aware file system and/or application (such as mkfs initially). > > But yes, just pointing mkfs to the chardev should be doable with very > little work. We can point it to a regular file after all. Note that I've avoided implementing read/write fops for dax devices partly out of concern for not wanting to figure out shared-mmap vs write coherence issues, but also because of a bet with Dave Hansen that device-dax not grow features like what happened to hugetlbfs. So it would seem mkfs would need to switch to mmap I/O, or bite the bullet and implement read/write fops in the driver.
