Hi Dave, > -----Original Message----- > From: Dave Airlie [mailto:airl...@gmail.com] > Sent: Saturday, May 05, 2012 7:23 PM > To: daei...@gmail.com > Cc: Inki Dae; kyungmin.p...@samsung.com; sw0312....@samsung.com; dri- > de...@lists.freedesktop.org > Subject: Re: [PATCH v2 3/4] drm/exynos: added userptr feature. > > On Sat, May 5, 2012 at 11:19 AM, <daei...@gmail.com> wrote: > > Hi Dave, > > > > 2012. 4. 25. 오후 7:15 Dave Airlie <airl...@gmail.com> 작성: > > > >> On Tue, Apr 24, 2012 at 6:17 AM, Inki Dae <inki....@samsung.com> wrote: > >>> this feature could be used to use memory region allocated by malloc() > in user > >>> mode and mmaped memory region allocated by other memory allocators. > userptr > >>> interface can identify memory type through vm_flags value and would > get > >>> pages or page frame numbers to user space appropriately. > >> > >> Is there anything to stop the unpriviledged userspace driver locking > >> all the RAM in the machine inside userptr? > >> > > > > you mean that there is something that it can stop user space driver > locking some memory region of RAM? and if any user space driver locked > some region then anyone on user space can't access the region? could you > please tell me about your concerns in more detail so that we can solve the > issue? I guess you mean that any user level driver such as specific EGL > library can allocate some memory region and also lock the region so that > other user space applications can't access the region until rendering is > completed by hw accelerator such as 2d/3d core or opposite case. > > > > actually, this feature has already been used by v4l2 so I didn't try to > consider we could face with any problem with this and I've got a feeling > maybe there is something I missed so I'd be happy for you or anyone give > me any advices. > > Well v4l get to make their own bad design decisions. > > The problem is if an unprivledged users accessing the drm can lock all > the pages it allocates into memory, by passing them to the kernel as > userptrs., thus bypassing the swap and blocking all other users on the > system. >
Thank you for your advices and comments and I will look over this feature again. We should use this feature for our linux-based platform because the backend of evas(used by elementary) or pixman(used by Cario) needs this feature to use hardware accelerator only using user address so I will re-post it again after resolving this issue if possible. Thanks, Inki Dae > Dave. _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
