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 > 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 > > Thanks, > Laura
