From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoffer Dall Subject: Re: [RFC PATCH v3 0/3] vfio: platform: return device properties for a platform device Date: Sun, 30 Aug 2015 16:06:38 +0200 Message-ID: <20150830140638.GB24113@cbox> References: <1419024032-1269-1-git-send-email-a.motakis@virtualopensystems.com> <55DF07F0.3070405@linaro.org> <1440691887.20355.27.camel@redhat.com> <55DF45D0.5040704@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <55DF45D0.5040704-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Eric Auger Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hi Eric, On Thu, Aug 27, 2015 at 07:16:00PM +0200, Eric Auger wrote: > Hi Alex, > On 08/27/2015 06:11 PM, Alex Williamson wrote: > > On Thu, 2015-08-27 at 14:52 +0200, Eric Auger wrote: > >> Hi Baptiste, Antonios, > >> > >> What are the plans wrt this series? I am currently integrating another > >> QEMU VFIO platform devices where this series could be useful I think > >> (Feb 2015). Do you intend to follow up and bring it upstream? > >> > >> Alex, do you see some show-stoppers in this series or do you advise to > >> simply follow-up? > > > > I'm at a bit of a disadvantage not really knowing what types of > > properties a user will be able to retrieve here. The interface itself > > seems sort of like a game of Go Fish. Should the properties we're > > looking for be generally available via sysfs? The ioctl proposed needs > > some work to fit within the argsz/flags model that vfio typically uses. > > It's unclear what argsz vs length represents and defining the flags > > field as 'type' limits the future extensions of the ioctl. Thanks, > > The properties that I need can be found in /proc/device-tree too. They > are of different types, with void cell value, with string cell > values(single & multiple), with integer cell value(s), array ... > > The aim is to be able to assign a highly configurable platform device to > a guest, read some property values on host and write the same values in > guest dt node. > Can you reiterate why QEMU and VFIO don't already have the information necessary to setup resources and present a DT to the guest that the guest can use? In any case, using /proc/device-tree seems brittle to me. -Christoffer