On 03/12/2017 12:05 PM, Daniel Vetter wrote: > On Sun, Mar 12, 2017 at 2:34 PM, Benjamin Gaignard > <benjamin.gaignard@xxxxxxxxxx> wrote: >> 2017-03-09 18:38 GMT+01:00 Laura Abbott <labbott@xxxxxxxxxx>: >>> On 03/09/2017 02:00 AM, Benjamin Gaignard wrote: >>>> 2017-03-06 17:04 GMT+01:00 Daniel Vetter <daniel@xxxxxxxx>: >>>>> On Mon, Mar 06, 2017 at 11:58:05AM +0100, Mark Brown wrote: >>>>>> On Mon, Mar 06, 2017 at 11:40:41AM +0100, Daniel Vetter wrote: >>>>>> >>>>>>> No one gave a thing about android in upstream, so Greg KH just dumped it >>>>>>> all into staging/android/. We've discussed ION a bunch of times, recorded >>>>>>> anything we'd like to fix in staging/android/TODO, and Laura's patch >>>>>>> series here addresses a big chunk of that. >>>>>> >>>>>>> This is pretty much the same approach we (gpu folks) used to de-stage the >>>>>>> syncpt stuff. >>>>>> >>>>>> Well, there's also the fact that quite a few people have issues with the >>>>>> design (like Laurent). It seems like a lot of them have either got more >>>>>> comfortable with it over time, or at least not managed to come up with >>>>>> any better ideas in the meantime. >>>>> >>>>> See the TODO, it has everything a really big group (look at the patch for >>>>> the full Cc: list) figured needs to be improved at LPC 2015. We don't just >>>>> merge stuff because merging stuff is fun :-) >>>>> >>>>> Laurent was even in that group ... >>>>> -Daniel >>>> >>>> For me those patches are going in the right direction. >>>> >>>> I still have few questions: >>>> - since alignment management has been remove from ion-core, should it >>>> be also removed from ioctl structure ? >>> >>> Yes, I think I'm going to go with the suggestion to fixup the ABI >>> so we don't need the compat layer and as part of that I'm also >>> dropping the align argument. >>> >>>> - can you we ride off ion_handle (at least in userland) and only >>>> export a dma-buf descriptor ? >>> >>> Yes, I think this is the right direction given we're breaking >>> everything anyway. I was debating trying to keep the two but >>> moving to only dma bufs is probably cleaner. The only reason >>> I could see for keeping the handles is running out of file >>> descriptors for dma-bufs but that seems unlikely. >>>> >>>> In the future how can we add new heaps ? >>>> Some platforms have very specific memory allocation >>>> requirements (just have a look in the number of gem custom allocator in drm) >>>> Do you plan to add heap type/mask for each ? >>> >>> Yes, that was my thinking. >> >> My concern is about the policy to adding heaps, will you accept >> "customs" heap per >> platforms ? per devices ? or only generic ones ? >> If you are too strict, we will have lot of out-of-tree heaps and if >> you accept of of them >> it will be a nightmare to maintain.... > > I think ion should expose any heap that's also directly accessible to > devices using dma_alloc(_coherent). That should leave very few things > left, like your SMA heap. > >> Another point is how can we put secure rules (like selinux policy) on >> heaps since all the allocations >> go to the same device (/dev/ion) ? For example, until now, in Android >> we have to give the same >> access rights to all the process that use ION. >> It will become problem when we will add secure heaps because we won't >> be able to distinguish secure >> processes to standard ones or set specific policy per heaps. >> Maybe I'm wrong here but I have never see selinux policy checking an >> ioctl field but if that >> exist it could be a solution. > > Hm, we might want to expose all the heaps as individual > /dev/ion_$heapname nodes? Should we do this from the start, since > we're massively revamping the uapi anyway (imo not needed, current > state seems to work too)? > -Daniel > I thought about that. One advantage with separate /dev/ion_$heap is that we don't have to worry about a limit of 32 possible heaps per system (32-bit heap id allocation field). But dealing with an ioctl seems easier than names. Userspace might be less likely to hardcode random id numbers vs. names as well. Thanks, Laura
