On 03/14/2017 07:47 AM, Benjamin Gaignard wrote: > 2017-03-13 22:09 GMT+01:00 Laura Abbott <labbott@xxxxxxxxxx>: >> 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 > > Should we use /devi/ion/$heap instead of /dev/ion_$heap ? > I think it would be easier for user to look into one directory rather > then in whole /dev to find the heaps > If we decide to move away from /dev/ion we can consider it. >> 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. > > In the futur I think that heap type will be replaced by a "get caps" > ioctl which will > describe heap capabilities. At least that is my understanding of kernel part > of "unix memory allocator" project > I don't think it will be completely replaced. A heap can have multiple capabilities so I suspect there will need to be some cap -> allocation instance translation. Of course all this is wild speculation since much of the unix memory allocator isn't well defined yet. Thanks, Laura
