On Wed, Apr 18, 2018 at 01:39:35PM +0300, Oleksandr Andrushchenko wrote: > On 04/18/2018 01:18 PM, Paul Durrant wrote: > > > -----Original Message----- > > > From: Xen-devel [mailto:xen-devel-boun...@lists.xenproject.org] On Behalf > > > Of Roger Pau Monné > > > Sent: 18 April 2018 11:11 > > > To: Oleksandr Andrushchenko <andr2...@gmail.com> > > > Cc: jgr...@suse.com; Artem Mygaiev <artem_myga...@epam.com>; > > > Dongwon Kim <dongwon....@intel.com>; airl...@linux.ie; > > > oleksandr_andrushche...@epam.com; linux-ker...@vger.kernel.org; dri- > > > de...@lists.freedesktop.org; Potrola, MateuszX > > > <mateuszx.potr...@intel.com>; xen-devel@lists.xenproject.org; > > > daniel.vet...@intel.com; boris.ostrov...@oracle.com; Matt Roper > > > <matthew.d.ro...@intel.com> > > > Subject: Re: [Xen-devel] [PATCH 0/1] drm/xen-zcopy: Add Xen zero-copy > > > helper DRM driver > > > > > > On Wed, Apr 18, 2018 at 11:01:12AM +0300, Oleksandr Andrushchenko > > > wrote: > > > > On 04/18/2018 10:35 AM, Roger Pau Monné wrote: > > > After speaking with Oleksandr on IRC, I think the main usage of the > > > gntdev extension is to: > > > > > > 1. Create a dma-buf from a set of grant references. > > > 2. Share dma-buf and get a list of grant references. > > > > > > I think this set of operations could be broken into: > > > > > > 1.1 Map grant references into user-space using the gntdev. > > > 1.2 Create a dma-buf out of a set of user-space virtual addresses. > > > > > > 2.1 Map a dma-buf into user-space. > > > 2.2 Get grefs out of the user-space addresses where the dma-buf is > > > mapped. > > > > > > So it seems like what's actually missing is a way to: > > > > > > - Create a dma-buf from a list of user-space virtual addresses. > > > - Allow to map a dma-buf into user-space, so it can then be used with > > > the gntdev. > > > > > > I think this is generic enough that it could be implemented by a > > > device not tied to Xen. AFAICT the hyper_dma guys also wanted > > > something similar to this. > Ok, so just to summarize, xen-zcopy/hyper-dmabuf as they are now, > are no go from your POV?
My opinion is that there seems to be a more generic way to implement this, and thus I would prefer that one. > Instead, we have to make all that fancy stuff > with VAs <-> device-X and have that device-X driver live out of drivers/xen > as it is not a Xen specific driver? That would be my preference if feasible, simply because it can be reused by other use-cases that need to create dma-bufs in user-space. In any case I just knew about dma-bufs this morning, there might be things that I'm missing. Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
