On Thu, 16 Mar 2017 12:05:19 -0400 J__r__me Glisse <jgli...@redhat.com> wrote:
> Cliff note: "Cliff's notes" isn't appropriate for a large feature such as this. Where's the long-form description? One which permits readers to fully understand the requirements, design, alternative designs, the implementation, the interface(s), etc? Have you ever spoken about HMM at a conference? If so, the supporting presentation documents might help here. That's the level of detail which should be presented here. > HMM offers 2 things (each standing on its own). First > it allows to use device memory transparently inside any process > without any modifications to process program code. Well. What is "device memory"? That's very vague. What are the characteristics of this memory? Why is it a requirement that userspace code be unaltered? What are the security implications - does the process need particular permissions to access this memory? What is the proposed interface to set up this access? > Second it allows to mirror process address space on a device. Why? Why is this a requirement, how will it be used, what are the use cases, etc? I spent a bit of time trying to locate a decent writeup of this feature but wasn't able to locate one. I'm not seeing a Documentation/ update in this patchset. Perhaps if you were to sit down and write a detailed Documentation/vm/hmm.txt then that would be a good starting point. This stuff is important - it's not really feasible to perform a decent review of this proposal unless the reviewer has access to this high-level conceptual stuff. So I'll take a look at merging this code as-is for testing purposes but I won't be attempting to review it at this stage.
