Le mer. 13 mars 2019 à 23:31, John Stultz <john.stu...@linaro.org> a écrit : > > On Wed, Mar 13, 2019 at 1:11 PM Liam Mark <lm...@codeaurora.org> wrote: > > On Tue, 5 Mar 2019, John Stultz wrote: > > > > > > Eventual TODOS: > > > * Reimplement page-pool for system heap (working on this) > > > * Add stats accounting to system/cma heaps > > > * Make the kselftest actually useful > > > * Add other heaps folks see as useful (would love to get > > > some help from actual carveout/chunk users)! > > > > We use a modified carveout heap for certain secure use cases. > > Cool! It would be great to see if you have any concerns about adding > such a secure-carveout heap to this framework. I suspect it would be > fairly similar to how its integrated into ION, but particularly I'd be > interested in issues around the lack of private flags and other > allocation arguments like alignment. > > > Although there would probably be some benefit in discssing how the dma-buf > > heap framework may want to support > > secure heaps in the future it is a large topic which I assume you don't > > want to tackle now. > > So I suspect others (Benjamin?) would have a more informed opinion on > the details, but the intent is to allow secure heap implementations. > I'm not sure what areas of concern you have for this allocation > framework in particular?
yes I would be great to understand how you provide the information to tell that a dmabuf is secure (or not) since we can't add flag in dmabuf structure itself. An option is manage the access rights when a device attach itself to the dmabuf but in this case you need define a list of allowed devices per heap... If you have a good solution for secure heaps you are welcome :-) Benjamin > > > We don't have any non-secure carveout heap use cases but the client use > > case I have seen usually revolve around > > wanting large allocations to succeed very quickly. > > For example I have seen camera use cases which do very large allocations > > on camera bootup from the carveout heap, these allocations would come from > > the carveout heap and fallback to the system heap when the carveout heap > > was full. > > Actual non-secure carveout heap can perhaps provide more detail. > > Yea, I'm aware that folks still see carveout as preferable to CMA due > to more consistent/predictable allocation latency. I think we still > have the issue that we don't have bindings to establish/configure > carveout regions w/ dts, and I'm not really wanting to hold up the > allocation API on that issue. > > > > Since we are making some fundamental changes to how ION worked and since > > Android is likely also be the largest user of the dma-buf heaps framework > > I think it would be good > > to have a path to resolve the issues which are currently preventing > > commercial Android releases from moving to the upstream version of ION. > > Yea, I do see solving the cache management efficiency issues as > critical for the dmabuf heaps to be actually usable (my previous > version of this patchset accidentally had my hacks to improve > performance rolled in!). And there are discussions going on in > various channels to try to figure out how to either change Android to > use dma-bufs more in line with how upstream expects, or what more > generic dma-buf changes we may need to allow Android to use dmabufs > with the expected performance they need. > > > I can understand if you don't necessarily want to put all/any of these > > changes into the dma-buf heaps framework as part of this series, but my > > hope is we can get > > the upstream community and the Android framework team to agree on what > > upstreamable changes to dma-buf heaps framework, and/or the Android > > framework, would be required in order for Android to move to the upstream > > dma-buf heaps framework for commercial devices. > > Yes. Though I also don't want to get the bigger dma-buf usage > discussion (which really affects all dmabuf exporters) too tied up > with this patch sets attempt to provide a usable allocation interface. > Part of the problem that I think we've seen with ION is that there is > a nest of of related issues, and the entire thing is just too big to > address at once, which I think is part of why ION has sat in staging > for so long. This patchset just tries to provide an dmabuf allocation > interface, and a few example exporter heap types. > > > I don't mean to make this specific to Android, but my assumption is that > > many of the ION/dma-buf heaps issues which affect Android would likely > > affect other new large users of the dma-buf heaps framework, so if we > > resolve it for Android we would be helping these future users as well. > > And I do understand that some the issues facing Android may need to be > > resolved by making changes to Android framework. > > While true, I also think some of the assumptions in how the dma-bufs > are used (pre-attachment of all devices, etc) are maybe not so > realistic given how Android is using them. I do want to explore if > Android can change how they use dma-bufs, but I also worry that we > need to think about how we could loosen the expectations for dma-bufs, > as well as trying to figure out how to support things folks have > brought up like partial cache maintenance. > > > I think it would be helpful to try and get as much of this agreed upon as > > possible before the dma-buf heaps framework moves out of staging. > > > > As part of my review I will highlight some of the issues which would > > affect Android. > > In my comments I will apply them to the system heap since that is what > > Android currently uses for a lot of its use cases. > > I realize that this new framework provides more flexibility to heaps, so > > perhaps some of these issues can be solved by creating a new type of > > system heap which Android can use, but even if the solution involves > > creating a new system heap I would like to make sure that this "new" > > system heap is upstreamable. > > So yea, I do realize I'm dodging the hard problem here, but I think > the cache-management/usage issue is far more generic. > > You're right that this implementation give a lot of flexibility to the > exporter heaps in how they implement the dmabuf ops (just like how > other device drivers that are dmabuf exporters have the same > flexibility), but I very much agree we don't want to add a system and > then later a "system-android" heap. So yea, a reasonable amount of > caution is warranted here. > > Thanks so much for the review and feedback! I'll try to address things > as I can as I'm traveling this week (so I may be a bit spotty). > > thanks > -john _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
