From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: NVM Mapping API Date: Wed, 16 May 2012 12:02:36 -0400 Message-ID: <20120516160236.GI22985@linux.intel.com> References: <20120515133450.GD22985@linux.intel.com> <4FB2E069.7060703@amacapital.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Andy Lutomirski Return-path: Content-Disposition: inline In-Reply-To: <4FB2E069.7060703@amacapital.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue, May 15, 2012 at 04:02:01PM -0700, Andy Lutomirski wrote: > I would love to use this from userspace. If I could carve out a little > piece of NVM as a file (or whatever) and mmap it, I could do all kinds > of fun things with that. It would be nice if it had well-defined, or at > least configurable or discoverable, caching properties (e.g. WB, WT, WC, > UC, etc.). Yes, usage from userspace is definitely planned; again through a filesystem interface. Treating it like a regular file will work as expected; the question is how to expose the interesting properties (eg is there a lighter weight mechanism than calling msync()). My hope was that by having a discussion of how to use this stuff within the kernel, we might come up with some usage models that would inform how we design a user space library. > (Even better would be a way to make a clone of an fd that only allows > mmap, but that's a mostly unrelated issue.) O_MMAP_ONLY? And I'm not sure why you'd want to forbid reads and writes.